well guys after doing alot of reading and hunting around i have finally bought myself a trials bike... a 2010 beta evo 250. I picked it up from manchester and it feels really good, its in excellent condition with alot of aftermarket parts fitted. pics are attached)  
as a noob to trials i have a few questions (as a motocross rider i know a fair bit about maintenance etc however i'm needing some pointers with the trials side) 
1, How often should i drop the gearbox oil from the bike and what oil should i use? i currently use elf fully synthetic moto oil is this suitable? 
2, what tyre pressures should i be running for general use? 
3, regarding premix are fully synthetic the oil to use and what ratio i.e 50:1 
4, how long will a full fuel tank last 2.5 ltrs (roughly) an hour or 5 hours? 
5, are pistons replaced regularly if so how often (i presume not very regularly due to lower average rpm?) 
i apologise for the list of noob questions but i am a total rookie at trials. any other advice regarding the sport would be appreciated.  
thanks in advance