Exercise releases endorphins which are known to positively effect libido - it makes sense the fitter someone feels the more energy they will have and libido works in tandem with this
Depends on age amongst variety of other factors of course - estradiol influences libido but if you have this in the range 10-30 pg/dl you should be ok as far as thats concerned
Few people benefit from
hCG added to
TRT regime - maybe you could try that although you would almost certainly need small amount of armidex every few days to keep e2 down doing this
Can't answer whether gels or injections are better for libido since no studies done on this and would vary from person to person in anycase
Whats your
DHT like on gel? - this is normally difficult to control on gels..would not have thought it has any negative impact on libido though but would speed up hair loss