Good advice here. A set of questions that might be easier might be along the lines of:
What is the economy like? (general prices on chests, xp lixs, and tokens should give you a feel for it),
Open server or Dominant Clan based?
If Dom, single controlling clan or competetive?
If single clan, what bosses do they kill? (both highest downed and those regularly killed),
If competetive, at what level? (how high of bosses, is greifing historically problematic),
If Open server, how is the economy for early game items?
Are there helpful low-mid clans? (either Dom or Open server),
Some general class tidbits that I believe are relatively consistent across servers:
Druids are generally the least-played class. As they are primarily healers they can be relatively hard to level, but a fun caster class. Since they are the least-played class, Druid gear is generally easier to obtain for most of the game. If you like the class-type and can grind through the leveling (having people to level with is huge for Druids), you can have fun with it.
Rogues are generally the most-played class. Many are used primarily for locking bottleneck bosses especially on competitive servers, and they are fun to play and generally considered pretty easy to level. However, as they are the most-played, Rogue gear is generally much harder to obtain especially toward endgame. If you don't mind a frustrating amount of competition/expense for gear,
this is a lot of fun.
The other 3 classes seem to vary, but tend to fall somewhere in between the other 2. A general breakdown of them can be provided by most helpful people if needed, but these are the usual outliers to consider when picking a class.
A further caution: picking a class to be helpful for a clan is a great sentiment, but it often isn't practical to go about it in that order. Pick something you will enjoy on a server with a reputable environment (or a challenging one if you want), and then get to know the people. It's a bit dangerous to pledge loyalty to someone and volunteer to do a lot of extra work to get attain their ranks, risking the chance that they're kinda a bunch of jerks lol.
In other news, Lugh is fun
Edit: might do well to answer my own questions lol
1 Dom clan that kills BT consistently, not yet killed Dhino. Varying competition from competing set of clans on up to Prot.
Could use more fire mages.
Don't really know how low-mid clans are doing currently, but in general, people try to be helpful, and most stuff up to mind tabs is pretty available.
Economy is meh. Chests for 60kish, hero xps 5-6k, pet tokens 30kish, mount tokens 65k and up. (some other Lughian that isn't as poor as I will probably have better approximations but this is a rough estimate).