Naw. I know rules were made to be broken but black and brown: no. Just no.
Stick with a classic black tuxedo and you’ll look good in all formal situations. Get a peach flower for your lapel if you want to tie your looks together without going overboard.
Yeah, it’ll work. Gray would be ideal but navy should look fine.
Depends on the situation.
For more formal, you can’t go wrong with grey. I also really like burgundy, navy, black, and tan.
For casual wear, most colors/patterns (even loud ones) can look good.
It’s tough to answer this because I don’t know your relative leg size but if you want maximum shrinkage go hot soak, hot dry. Although I wouldn’t recommend the dryer, as it gives you really weird creases and fading.