Senior ball rules state that you have to live in the state or touch the state that the team is from, that state is determined by where the majority of players live, not where the sponsor might be or the manager might be.
Best tourneys again are depending where you live but here are some of the bigger ones (you can find the dates on each site):
SSUSA (West Coast based but presence nationally, strong 40 program on both coasts)
Spring World Championship
World Championships in Vegas
ISSA (East Coast based, limited national presence)
World Championships (Richmond)
40 - 50 division split into 3 levels, AAA, Major and Major Plus, each team allowed to add 3 players who are 1 level above (just like the 3 chip rule! lol). SSUSA big tourneys are 5GG (2 or 3 play-in games to determine seeding) then either 3GG elim or double elim (depends on how many teams in your division). ISSA strictly 4GG, 2 play-in and double elim.
There is also SPA, they are Mid-West (OK) and there are smaller assoc. USSSA Sr program has not really taken off but they have better presence in a few places.
Hope this helps and good luck!