I cant give you advice on all that, but here's what i can say:
1. the bridge is an easy drop in install (unless you bought the saddles only..which means you have to take out the jag saddles and replace them with the mustang saddles, which is what I did.) Saddle replacement can be a bit of a tedious job, but once you get it, its an easy, moderately quick install.
2. Strings. Go for whatever gauge you like. I use EXL110s on my Jag, and they are just right. If you go for a heavier gauge, they will not slip as much on the Jags saddles (and therefore possibly cause you to re-think replacing them with mustang ones...check it out first 😀 )
Can't help with switches, as i havent done any mods to my Jag besides the bridge. next up is some SDJAG-1s
