better reassess your questions.
2) yes. offroading kills parts. especially transmissions with water in them.
3) yes. but all are prone to the same kinds of maintenence issues caused from offroading.
1) depends. are you going to do the same thing that killed the first tranny? whats wrong with your tranny now?
if you have grown to love wheeling, time to start learning routine maintenence and general repairs..... otherwise it will get costly.