Proportional flap knob....
1) There are no system upgrades available for any JR systems except adding CCPM to a few older systems like the 347, 388, and older 8103's.
2) The 378 would be the least expensive system that has the functions you are looking for. It has a digital rocker switch for the flap and aux 2 channels. The 8103 has rotary knobs, and the 10X has slide switches on the case sides.