Alrighty, let me see if my memory works and if I remember all your questions:
(1) I'm blind as a bat, and learned on my first trip to have all essentials, like my prescription dive mask right on my paw. Think of it this way, if you don't want to live without it, carry it on with you. All my important stuff is in my carry-on.
(2) Good question re the weather..I left on 3/4, my guess, probably good, but ask others. Or just check the weather thingy on AOL.
(3) Do you want to buy flowers to have in your room, or seeds to send home? Oddly enough, all these nine years, I've never seen a seed for sale on AC. Nor, a flower shop. If anyone does, please enlighten me! I don't know where you are staying. My pet, Paradise Resort Hotel puts flowers in my room every day. They clip it from the grounds. You could check with your hotel. PRH had, one day when I was in the office, a huge bouquet to take to a honeymoon couple, and I gues most hotels would do the same. And if the place has flowers on the grounds, they won't mind, I should think, if you snip a few to hand to your loved one. I take hibiscus for my front porch every day, over what the hotel does for me. Needless to say, it is appropriate to ask first. And, if it is special day, all the hotels will do something nice, if you ask. At PRH, they just do it. On Valentine's day, we found a huge heart on our bed made of bouganvilla brachts. On my birthday, we came home to find balloons and flowers everywhere. All Belizeans are generous folks. Of course, we have a history with PRH, so you may have to ask first, for the flowers at your place, but most Belizens gladly will take good care of guests. And, if you go awhile, they will attend to being nice to you.
(4) Now, and I wish I was going, too!!!!!!!!
(5) What can fit under your seat is the restriction, and that is not too big. Only two bags total, so pack light or you may have to cough up an extra $40US per bag, if the agent is paying attention.
(6) Never had a problem with thievery, but I am a former airline employee, and am the queen of packing light. I get all my dive stuff in the small regular bag, that I used to be able to carry on. You know, the one with the cart. I squish in my three pairs of shorts and three tees. Gym shoes to go in, and a pair of sandals. So, it is not as obvious as a dive bag. Propably a smart idea to avoid big, fancy dive bags, although, back in the day when I used one, I never had a problen. Just a pain to tote. Probably, I haul more cosmetics than cloths...I am a tad vain. This year, since we went over my birthday, I did take a pretty dress. I wash out stuff every night and hang it up to dry. Works for me!!!!!!!!
Have a great trip. I am a low maintenancce traveler, and perhaps you like more, so keep checking this site. You might find more info more valuable to you.