1) Depends on hunting pressure ect, but often you can get away with minimal disturbance, some times animals dont react at all. Normally they hear the 'sonic boom' but it appears directly above them so they do not know where the shooter is. So you can get a few more shots away before they know whats up
2) Mounts? this for suppressor's to fit more than one rifle. Usually the manufacturer can make removable alloy/plastic collars for different barrel profiles.
3) They still recommend hearing protecting with a suppressor, most reduce 20-30 Decibels, so it is still loud. I find it is reduced enough to not need it, but thats me.
SHORTEN your barrel. trust me. nothing worse than a 24" barrel with a can on the end, makes for a very cumbersome rifle. Go for an over barrel suppressor and I like to make it as short as possible so the end of the can is near the end of the stock, this means you dont really add any weight as you cut a off quite a bit. If the can is 4-5" forward of the muzzle you can take 3-4" off and you will not loose much velocity if any at all.
Suppressors heat up real HOT! especially on big magnums, be aware of this, try not to shoot strings of shots, unless you have to. Neoprene covers can hep reduce heat mirage from the suppressor.
You will normally have a vertical POI shift with the can on/off. good bedding and shorter/stiffer barrels reduce this.
My advice form across the ditch(New Zealand) where suppressors are pretty standard on new rifles now, is buy an aluminium type can with stainless muzzle brake,one piece internal. I have seen Americans talk about titanium cans and you dont need them, you are paying alot more. There are professional guys I know who have put 10,000+ rounds through alloy cans over years of field culling at they work fine.
I dont know what your guys laws are on importing cans but maybe worth having a look at ones made here in NZ or Europe.
We normally pay $400-$700 NZD for one fitted and some new models are down to 9 Oz for standard calibers.
http://hardyrifleengineering.co.nz/index/
http://gunworks.co.nz/
http://www.dpt.co.nz/
http://mae.co.nz/
