First, you will likely need some way to charge the batteries. Outboards have very poor battery charging capabilities.
Also, the porta-potty isn't going to cut it in most areas. In some areas, porta-potties aren't allowed, unless they are permanently mounted and of the MSD type with a deck pumpout fitting, which I doubt is the case with yours. Having a proper marine head with holding tank that is setup for both deck pumpout and self-pumpout would make far more sense.
Fixing the autopilot and making it more reliable will be useful.
Having more water carrying capacity as well as fuel capacity would be wise. In some areas of the Caribbean potable fresh water is not-free. Having more capacity allows you to skip areas that have poor/expensive/contaminated water.
As for rules, fees, etc., you should look at the various countries on noonsite.com.
For route planning, I'd recommend you pickup a copy of Jimmy Cornell's World Cruising Routes.
As for where to stop...that can depend a lot on what your budget it.
I'd point out that the more self-sufficient the boat, the less expensive it will be to stay out cruising long term.
An older friend of mine and I are sailing to the Bahamas in early October. I am 31 he is 65. He is paying for food and docking and such. I provide the boat.
Likely will decide to sail farther south to Puerto Rico and who knows from there. Possibly farther south if I don't run out of money. He probably won't be with me then.
The boat is a 1974 Grampian 31' sloop rig. It doesn't have a shower only a porta potty. No radar. No liferaft. No Eperb. No watermaker. It has two 20 gallon water tanks and no inboard motor. It has a Tohatsu 9.8 hp outboard instead. It has no spare sails only the roller jib and heavy duty 3 reef main. The autopilot is the tiller kind and it has gone out before. It will have a dinghy soon.
Any suggestions for equipment, snacks, food, water, medicine (Money Saving hints is a plus) also, rules, fees, languages, lingo, weather, currents, routes, places we should stop, that I should know about.