glideher

i use soft lipos all the time, just make sure to cover it well with electric tape or even make a nice housing with wood or aluminum, usually they use hard casing for cars to prevent punctures from rocks or crashes

to transmit the signal, you would still need a radio system, Rx and Tx, but surely you will be able to use a computer to map out your way points, etc. just like quad copters via arduino

Feather² Squared, only 47 grams with a wing span of 38.5 inches

yes flaps can be used on a Y lead wire, you will not need a BEC, you can always use a 1s or 2s lipo directly connected to your receiver to power up all your servos. if you wish you may use a BEC, smaller and lighter weight 2grams. but i have always used direct connection to receiver with a 1s or even 2s lipo, i use Spektrum Rx Tx. hope this helps rc gliders