hide glue and titebond both work with sinew. titebond can be #1,2 or 3. Referred to as TB3, TB2, etc on tis forum (not to be confused with tbb1, tbb2 (traditional bowyers bible). Hide glue gives the best backing performance according to many. , but is succeptable to moisture much more than TB.
backstrap and leg work the same- but
backstrap is easier to process (shred)
backstrap is longer
legs can be very long too if stripped from the carcasss right
as far as ammount- hard to say... someone else will chime in
good luck