Chas ,
#1. Probably more than you'd think use a 'pistol' type radio system. Can be awkward, but certainly possible. If you're comfortable using one, then why not?
#2. The quick and dirty answer is, No. It takes more than just swapping a crystal, and is usually cost prohibitive. (Don't bother) It depends on the particular radio too.
#3. Sort of like asking what's the 'best' car to drive, and if you're a Chevy or Ford 'nut'. Probably the best bet is to select a fairly common 'name brand' available to you locally. Get what ever brand you like.
Wanna try different things in sailing? Have at it! Just use some common sense when you try them. Some things (just like in flying) will work, sort of, and some things probably won't. Getting a little experience first (just like in flying) cuts down on the 'goofs', sort of. If it sounds like fun... give it a try.
- 'Doc