Those rubber things are brush busters and not needed at all. They are meant to keep brush and briars from getting in the space of that recurve.

As far as strings, it depends on your arrows. A dacron should make an arrow show stiffer reaction and a fast flight will make it show weaker. My dreamcatcher shows a stiff reaction on all arrows I tried so I ordered a high performance string to weaken the arrows some.

Try some bare shaft testing and see what happens. I would try the dacron first, and go from there.