Average used bandwidth is very low. I haven't tested it recently but it used to be possible to run WoW off a 56kbps dial-up link, implying a download rate of probably 6kBps or lower. The latency tends to be a much greater issue, as creatures/players may not be where your client shows them as and it can impact upon spell casting delays, etc.
By the way, if that connection really is 256 mbps, that's faster than almost all of Australia and New Zealand plays WoW at - that is 32 MB/sec, and we tend to top out at 10-20 MB/sec.
In terms of classes, trying to cover all three roles between the two of you is a good target. When you guys are questing together by yourselves, having one person be DPS and the other healing helps keeps downtime to a minimum. And if you guys decide to use the Dungeon Finder, having one person able to heal and the other be able to tank ensures you'll never have to wait long in the queue.
Blizzard has homogenized the classes over the years so there is a tremendous amount of overlap between the classes and specs. As long as you guys cover the three class roles, feel free to choose whatever fancies you.
For reference the hybrid classes are:
- All three roles: Paladins, Druids
- DPS + Healing: Priests, Shamen
- DPS + Tanking: Warriors, Death Knights
If you're going to take my advice about role coverage, you'll want to avoid Mages, Hunters, Warlocks, and Rogues as they can only be one role: DPS.
Since you're talking 1-85 play, Death Knights are off the table as they start at level 55.
Putting it all together:
- Person 1: Paladin, Druid, or Warrior (to cover tanking)
- Person 2: Paladin, Druid, Priest, or Shaman (to cover healing)
In terms of professions, I'd avoid the heavy crafting professions that take a lot of time to level up and are usually taken for the Bind-on-pickup endgame recipes: Blacksmithing, Tailoring, Engineering, Leatherworking. Instead, focus on the professions that'll let you help each other out while leveling, like Enchanting and Alchemy, or the gathering professions, like Mining and Skinning, which will prove lucrative and won't require too much (if any) time soloing.
Best Answer
Short answer: Yes
Longer Answer: Yes, you can use them as long as you have the necessary skill for the item (i.e. you can't wear the plate chest with your druid). The EXP-Bonus will work (tested this myself with my cloth wearing druid ;) ).
However, the stats on said items may not be exactly what you are looking for, but I guess this is really obvious. :)