Just started dual boxing a couple of teams in SWTOR. The lack of an Interact with Target function within the game is probably the biggest thing to get used to after boxing WoW off and on since 2008. Yesterday I tested running 2 dps (Lightning Sorcerer Sith Inquisitors) with companions (one set to tank, one set to heals) through a standard difficulty dungeon. It was a cake walk. Companions were completely overpowered last expansion. They're not quite as strong anymore, but still plenty strong for something like this. Only came close to dying once during a strange fight where one of my characters couldn't see the mob the rest were fighting so they attacked a different pack.

There are a couple of people out there who actually run the dungeons (Flash Points in SWTOR lingo) at Master Mode (aka Heroic) difficulty solo, with just a healing companion. So I imagine most of the master mode dungeons will be quite possible dual boxing. Sadly companions can't come into raids in SWTOR, so you'd have to box more accounts to do it.

SWTOR vocab:
Flash Point = Dungeon
Gear levels: White - standard quality, Green - premium, blue - prototype, Purple - artifact, orange - legendary (very easy to get purple, basically have to be max level to get orange)
Dungeon Difficulties:
-----Story Mode: super easy mode designed for a solo player to get through the content for the purposes of experiencing the main storyline. Rewards are minimal, but better than standard quest rewards. I think it's blue gear, one step up from quest green. Some crafting mats too.
-----Veteran Mode: Standard difficulty. You character's level will be locked to the level of the dungeon. If you're lower, you'll be boosted but you won't have any additional abilities. Rewards are pretty good, purple gear and crafting mats.
-----Master Mode: Heroic difficulty. Much harder and often with additional mechanics for the bosses. Drops end game gear. Not sure if any of it's best in slot, but I think it is. Highest level crafting mats, including mats that can only be found here.

Alacrity = Haste
Presence = the only stat that directly improves your NPC companions' power in combat. Weapons and armor are strictly cosmetic for them.

I'm sure there's a bunch more but that's off the top of my head.


Things I've learned so far from going through low level content that's different from WoW (also, I'm subscribed so some of this will be different if you going the free-to-play route):
-There are no macros in SWTOR
-There is no interact with target. You need to right click with the mouse to interact, no other option.
-Running two of the same class and specs is the easiest since they will have the same abilities and rotations.
-It's very possible to run different classes at the same time, but it won't be as effective unless their rotations somewhat match with regards to ability cooldown timing, number of abilities used in a standard rotation, and differences in alacrity (aka Haste) between the characters causing a different GCD timing.
-Auto-follow is really bad in some ways, but better in others. It's bad in that it will drop if you hit your Acquire Target's Target button or mount up. Also, your following characters will randomly fall through the floor on a very few ramps/stairs and die immediately. This will only happen rarely, but most of the time they will be fine on the exact same ramp/stairs. Not a big deal, just annoying. Sometimes it will look like your other players aren't following, but if you check their game window, they are in fact following. Switching who is the leader back and forth often fixes this.
--Auto-follow in combat causes following characters to drop enemy targets, so you'll need to have them re-target after you're done moving them.
--Auto-follow seems to use the same pathing algorithms that the game uses for your NPC companions, so your following characters will generally walk the exact same path you did. If you drop down from somewhere or jump up somewhere, they will take the long route to get back to you even if this is outside of the normal follow distance. Basically like WoW pet pathing, so they can cause mob trains if you're not careful. Best to make each one drop/jump individually.
-The non-main characters will often look like they're not facing enemies, but they'll attack regardless so it's just funny looking.
-Crafting is done by your companions and everything being made takes real world time. Crafting will happen even if you're logged out, so end game stuff that can take 15 minutes or more can be queued right before you log. The companion's level (basically an affinity level) affects the time it takes to craft and the time it takes them to run crafting missions.
-You can only have one production crafting skill per character (lame). Crafting is super restricted for non-subscribers.
-For story quest instances (and there are a metric f-ton of them in this game), each character has to run through their own, even if they're the exact same class. So the more characters you box, the more times you'll have to repeat the same instances. These are often caves/buildings/small areas where something happens that advances the plot. They usually take a few minutes per, even if you rush through. The exception would be if you're playing a stealth class, then you can just skip past the combat and go to the quest point. (this is why I'm happy just dual boxing)
-The in-game store is WAAAAAY more extensive here since the free-to-play portion of SWTOR actually goes to level 50 (70 is the max right now). There are a ton of really cool weapons and armor available that can be used just cosmetically, or functionally if you fill in all of the different item slots in each piece (expensive).
-The in-game store uses a virtual currency called Cartel Coins and costs real money.
-You get something like 500 or 600 cartel coins each month you sub. (this isn't enough for any of the really cool stuff unless you save up a couple of months)
-You can get 100 free cartel coins each month for having an authenticator attached to your account. The virtual authenticator (it's free) counts for this too.
-Standard currency is credits, and there are no value tiers (copper < silver < gold, etc)
-You can unlock a bunch of stuff permanently for your entire account using credits or cartel coins. Credits is obviously much more expensive and generally has level or other requirements while the cartel option can be done at any time.
-Leveling one of each main class (8 total between the Sith and the Republic) gets you some nice bonuses: your class buff will grant you the bonuses of every core class (4 buffs in one basically), and your Heroic Moment gets one additional ability from each of the 8 classes (so it starts out with none)
-You can own multiple homes that are personal instances you can decorate. This is basically a mini-game but is completely optional.
-You can run space fighter missions (space PVP and I think some PVE). Also completely optional. Your ship can also be upgraded a bit.
-You can run PVP. There's a couple different flavors (including hutt ball), but I haven't done any of it. Pretty sure there's ranked PVP.
-There are 8 different core storylines covering the 4 main classes from each faction. These storylines actually overlap each other so you won't see the whole story until you finish them all. This covers vanilla SWTOR. All of the expansions only have two different stories, one for each faction.
-The main classes are mirrors of each other, it's just the flavor of the abilities that change.
-Guilds can get guild capital ships, basically just instanced guild housing. Guilds can offer up to a 15% xp boost, among other boosts that can be selected.

There's a ton more but this is probably a bit much as it is.