In all honesty, I wouldn't spend too much time trying to gear a bot. They're pretty poor, the dps bots steal aggro even while doing the tiny bit of dps they put out, they're pretty difficult to control (planting mob all over the place), and they leach a full player's worth of exp while doing 1/50th of what an actual player can do.
They're somewhat decent at healing while you're leveling, and a pally bot does a good job of tanking/mild heals, but they're more hassle than they're worth once you hit 70, get a few defensive AAs and some gear from the 55-70 zones.
As for classes, any of the tanks will suffice. Note that warriors have a lot more access to defensive abilities, and will be able to tank the big guys longer and more often. Knights are great in a pinch or for short fights, and are a lot better at aggro early on. Knights are also great at supplying utility (sk gets a group buff "Death March" that increases dps and adds a heal proc, pallies have some nice stuns and heals). I'd definitely recommend a knight over a warrior in the group game, warriors edging them out against beefier targets.
If you don't choose a paladin as your tank, I'd definitely go with cleric. Druid/shaman are decent at single target heals, but a group without someone who can spam group heals/cures is asking for disaster imo

BL is always the dps class I recommend for players new to the server. Unranked T8 pet (buyable from other players) makes it by far the best damager you can find before you get into T8 with rank 3 spells and gear, which is a loooooong time if you're going through the content honestly. Note that the sk also gets an unranked T8 pet which does kinda sorta OK damage early on (probably more than most t3-ish players), but is never used in the upper tiers and might be pricey depending on who you buy it from (doesn't drop off anything, the sk has to purchase it with points earned in HoH.) If that helps
