First, do NOT go to SSBB with all your luggage in the car!!!!!! Can I say that again?? NO. If you are doing only carry-on, you could do it, so long as you take your luggage with you.

I would not worry about the weather forecast, as weather forecasts on island are even more a 'suggestion' than they are at home. Unless there is a tropical wave coming through, showers come through and are gone.

I'm not sure why you need to buy a small pair of scissors on island. If you need them, just bring them with you. With regard to sunscreen, there are lots of places you can buy it on island. As far as bugspray, if you are a bug magnet, yes, I would bring it.

No test required if you are vaccinated, yes. Arriving from SJU, hopefully you will avoid big crowds at immigration, which of course is an advantage.

Please post pictures and a report when you arrive!! Looking forward to it!!!