I did my component transfer about seven years ago, and they credited me my BRT and gave me one year towards my promotion. (time credited towards promotion is dependent on your B-class employment I think?)
The recruiters will try to steer you towards the trades that they need right now. Be aware though, that most operator trades, and bos'n's, have a high attrition rate. That's because op trades are pretty dull when you're not deployed.
If you have the apptitude, I'd recommend any engineer trades (ie. naval weapons tech, marine electrician, hull tech, or marine engineer[stoker]). These trades are in high demand.
Good luck. Hope you get a good one.
LS Thompson A
E Tech