as for the loop-unit i would recomend the RJM RG-16, this unit has 8 audio loops (4 inline, and 4 independent), an inputbuffer, tuner out - as well as switching outlets for the 8 switchingoptions of the roadster head (with only one cable from the RG-16 to the footswitch input of the amp) and a second outlet for another amp. but the two switching outlets are wired in parallel, so you can´t do independent switching of two amps, but it works well and Ron (the owner of RJM) can build you a special-amp cable as well, if you want something special.
as for the footcontroller, you can use any midi-controller you like.
i would prefer one like the groundcontrol pro or the rocktron all access, or you use a behringer fcb1010 with the UnO software upgrade - why? simple: all those midi-boards can handle instant access (control-change) messages to turn on loops like you turn on a stompbox in front of you.
