Welcome to boxing!

I'd go with RAF, and get several combinations... you never know what you'll want to play down the road.
Classes that can be several roles (spec DPS, Heals, Tanking) are more flexible.
Classes that can spec DPS (or ranged DPS in particular) are going to be easier to level.
I liked Shamans and Druids a fair bit.

Everyone has their own preference.
My favorite PvE (5-man content) group was: Protection Paladin, Destruction Warlock, 3x Elemental Shaman (one of those was dual-spec, Resto).

Some classes don't get all of their tanking tools, until down the road.
Druids in particular are missing tools for a lot of the lower level dungeons, making those a bit harder to do.
But by maximum level (or 20 levels under cap), everyone has the tools... and it's a question of the flavor you enjoy.

You can drive with just about anything.
In general, this is going to be the tanking toon.
You can switch between toons, for perspective quite easily.
Independent slave movement keys, will break follow for you, which is good so the casters stay well back of the tank.

I've found it very nice to have a Shaman on the team.
A Resto Shaman is an easy healer to have, between Chain Heal, Riptide and Earth Shield.
The self rez (if you're far enough back from whatever kills the group) is nice.
If you have an Elemental/Enhancement Shaman on the team, the Resto obviously adds a bit less... similarly, if you have another class that can provide the equivalent to Heroism/Bloodlust, that reduces the need for a Shaman too.

You're not really going to need a Mage for Portals... especially with Dungeon Finder.
The flexibility is nice, don't get me wrong.
But if you have a Tank character, a different character who can Heal and three more... you can do gear/level appropriate dungeons, without ever leaving your home city.
Once you've done questing, to maximum level... dungeons are a major occupier of your time.
You can do Dailies or Faction or whatever... and having extra mobility there is nice.

I'd stick with the basics for now.
You don't really need a million hot keys.
The G600 mouse gets you a lot of mouse buttons.
You can use the Keyboard too, especially say Alt + KEY and Ctrl + KEY and Shift + KEY.
That's a lot of combinations, without needing Alt + Ctrl + KEY.

An attack key, a follow key, and a break follow key... that gets you started.
The wizard will easily provide you with those.
As you need to overcome something, in your boxing quest, think of an option that would help you... then add that to your setup.
The AoE, Panic, Burst, etc... are definitely things to think about, but you're not going to need them initially.

You could have your healer assist off of the mob.
And do either an AoE or Single target heal.
That would cover a lot of your healing.
#show Chain Healing
<Insert Assist... or include in the Combat Keys from IS Boxer>
/cast [help][help,@targettarget] Chain Healing

The Grid/CustomLayouts/Clique... or Healbot or Vuhdo (each a stand-alone option instead of three addons) gets more flexibility, which is worth looking at down the road.
You can also use Full Screen Stacked, as your window layout... and then have Video Feeds and interact with those... as another means of heals.

Macros are great.
Start simple... and go from there.
There are a lot of resources on the site for macros.