1. Yes you will be fine with geography. You do not need a degree in engineering. I know fellow F/A-18 pilots who were music and psychology majors.
2. You are not too old.
3. If you want to stay in aviation, NFO - then it is jets or big planes. Personally I think SEAL or EOD (explosive ordnance disposal) are very cool, but also very hard. Not that getting jets is easy, but it is a different kind of hard.
4. I really don't know, but I'm sure it would set you back some.
5. If you become a pilot the your CFI will still lapse unless you do that on the weekends. Multi will be not current depending on what you fly because Navy jets are considered multi with centerline thrust. The big planes would be fine for multi. Helos - you would not be current on multi airplane, but you would still be building turbine time, just not turbine airplane time.
If it were a non flying job, then you would probably want to get some local recurrent training and then back in with the CFI thing to build some currency hours before trying at the regionals.
While I am getting out of the Navy at the 11 year mark I wouldn't trade my time for anything. Flying from the ships (whether planes or helos) is the coolest thing in the world. Landing on them at night is the scariest thing in the world. No offense to the Air Force guys, just my opinion.