Does the clutch have any adjustment in it?
Could be worth altering that, for the biting point issue you're having.
The throttle... Whenever you simply let go of the throttle on a V-Twin, it will lurch forward (or rather throw you forward), as that is the nature of engine braking on a vehicle with lots of low-end torque. Consequently, whazzing it open and feeling the reverse is also a feature of low-end torque. That's the raw muscle of a Cruiser and one reason we love them so much!!
Give it another go, but be properly gentle on the controls.
As I recall, you're around Reading somewhere?
If you like, I can nip round or meet you somewhere local this weekend and have a look at the bike, offer a second opinion?