A1:
The hook of Umbrella fly is located far beneath the extended body therefore it does not block striking and hooking.
There is an enough space "Z" between the eye and hook point which is most important element of hooking ability and the space "W" that the extended line from a hook point does not cross over to the eye is another element in the hook geometry.

A2:
The under hackling holds the fly higher in the surface tension of water and it keeps a fly on the surface film.
We suggest full 3 turns in clockwise hackling and tied in the hackle at 4 turns in alomost case. But you may increase the turns if you fish in the free stone stream or change from extended feather body to the tube body.

A3:
It does not happen to twist a tippet due to the balance of umbrella fly even fine tippets 7X, 8X. The problem is the casting stroke which develops the trouble, too much false cast, non-paralleled casting plane and .....
It is not caused by the fly construction.

Barb less Umbrella hook tune up
If still you consider the poor hooking ability and keeps higher hooking capacity, we suggest to make tuning of hook. It increases a chance to pierce the hook into the upper jaw of fish.

Normal

Tweak a hook point

Normal

Parallel hook point