It can be fairly overwhelming at first. I practiced all the macros first on a training dummy.

As far as the necro goes, I'd say play what is the most fun for you. As more veteran members of the board will attest, your group will already be more efficient that your common PUG, simply because you created the characters to fit the team; you didn't create a team out of existing, pre-made characters, so to speak.

There's a lot of info on these boards concerning macros, etc. I think it's best to keep it simple. Find the most useful CA/spells for each class and use them over and over. I use about 6-8 CA/spells per toon, spread across 3-4 keys (2 CAs/spells per macro). While I may not be utilizing everything in my inventory, this keeps it easy to manage. This also may change in the future as my team levels.

As far as commands being sent through the SK, that's exactly how I play. My macros are roughly setup like so:

1: SK pre-buff (not assigned to any other toons)
2: SK single target taunt (not assigned to any other toons)
3: SK Taunt, Toons/Defiler Pet assist + 2 CAs/Spells (fight buffs/debuffs)
4: Debuffs
5: Damage
6: Damage
7: Damage/Positional damage (backstabs for Dirge and Swash...start with Walk the Plank so the mob is facing away for both Dirge and Swash)
8: AOE/Encounter if toon has it
9: Can't remember...another AE?
0: Attack/Spellcasting Off
- : Follow
=: Stop Follow
F1: Target Tank
F2: Group ward
F3: Group Heal
F4: Cure Tank
F5: Ward/Reactive Tank
F6: Single Target Heal Tank (Inq/Defiler)
F7: Single Target Heal Tank (Inq/Defiler)

And that's about it. It works for where I'm at but I know full well it will probably grow in complexity. For instance, I have yet to mez anything. I don't have a button for battle rezzing, etc. I still manually click Escape if I have to (yikes!).

Anyways, your setup will change as you move through the levels. There's a wealth of info here on the boards that was absolutely invaluable to me when I started. In fact, I still read old threads simply because it may apply to me now as opposed to 30 levels ago. Also check out the wiki, got heaps of good info on it.