that’s a lot of questions 🙂
1/ RLT AMR is in B10 onwards only.
2/ If all trx pref mark are equal, the less interfered trx is favoured. If all trx are equally interfered, the last trx is always favoured for cs traffic. The ps traffic will be allocated on the first trx. This strategy is to have consecutive pdch allocation of ps traffic, without getting disturbed by random tch allocation.
If you don’t notice that the less interfered trx is favoured… then it’s probably because
a) you are using hopping (all trx equally interfered)
b) your interference bands are not “fine” enough, you should resize them.
3/ PDCH can be forced onto the BCCH TRX by default (if timeslots remain), thanks to the parameter PREF BCCH GPRS (or something like this)