Rosko,
I ran a few thru the chrono and might be able to help........
Mine at 30" and 70# shot a 375gr arrow at 319fps. That' s with a string loop and Leeches only.
So for you with 2" less draw and a 10gr heavier arrow than my set-up,I would expect you to get somewhere in the neighborhood of 295fps+/-
Also, don' t just assume that your bow is 70# because its a 70# model.........I had to turn mine out almost 3/4 of a turn to bring it down to 70#.

As for your other questions......I scrapped the Hush Puppies the day I got the bow. They aren' t BAD, but to my ears the leeches are better, and they are also lighter.....
Place them close to the cam ends of the string and you' ll lose less speed.
As for the Vibrablocks.......I always slide mine down tight to the limb pockets, and then install a set of limbsavers as usual. The vibrablocks to me feel heavier so I just move them down where they can' t affect speed, and put the lighter limbsavers on. I meant to do a speed comparison with the Vibrablocks at the ends vs. the Limbsavers and also the SIMS Leeches vs. the Hush Kit silencers and just plain forgot.