Hi there,
A1) the newest controller is the R30iA controller
A2) no, you can not keep the robot and connect an R30iA controller to it.
A3) no, you can take our RJ2 TP programs and load them in your R30iA controller, i would advise the first time you run it you check it line by line.
A4) the newest models are LRMate200iC, M710iC series, ArmMate 100iC robot, have a look at
http://www.fanucrobotics.com/24_987_Robots+A%2DZ.html for more details.
For price i would advise you to contact your FANUC supplier, same for warranty.
have fun