2005 Ford Explorer Towing capacity question

New to this forum and have an 05 Explorer Limited with the 4.6L V8 and an automatic tranny. It is the 4x4 model. I have a couple of questions I could use help with. Explorer has almost 200,000 miles on it. Original motor and tranny. Well maintained.

1. I have a Class II hitch on my Explorer so I assume I only have the 3.55 rear axle ratio, not the 3.73. Does anyone know how to confirm this?

2. I am buying a 24' deck boat which, with trailer, will be about 5,000 lbs. Does anyone have an opinion as to whether I'd fry my tranny if I simply replaced my Class II hitch with a Class III hitch without swapping out the rear diff?

3. If I need to go all the way in order to tow this kind of weight is there anything I need to do other than a) Swap to a 3.73 rear diff, b) swap to an OEM class III hitch and c) swap the power/light connector out if needed?

Should I make sure I have trailer brakes.

Love my Explorer but I'm worried about putting $500 - $1,000 to swap everything and then blowing the tranny or something else.

Any input would be appreciated.

Rob