I can't say too much about what squash are going to be good to eat at a young stage, but Baker Creek has decent information in their online catalog.

As for pumpkins for hot climates I might advise the Calabaza squash (available at www.sunriseseeds.com) or any of the C. Mixta varieties. Any of the Thai pumpkins are also good choices.

I remember two or three years ago I had a Big Max pumpkin that was suicidal (if it had kept growing it would have crushed the very vine it was on) I cut in when it was 4- 6 inches wide and ate it as a summer squash. It was pretty good, if I remember.

This year I am growing Kumi Kumi, a Maori/New Zealand winter squash that is also traditionally used when young as a summer squash and has the added attraction of having hulless seeds.
I'm also trying a South American squash, Zapallito de Tronco, that came out first in a Master Gardener's trial for flavor and texture (round summer squash) I'm not sure what it's like when mature but I'll let a couple go to find out. It's extremely productive too.
I think I remember Trombocino d'Albenga (sp?) as being just as good when it gets mature as when it's smaller.

I ordered the Large Black Thai Pumpkin seeds, planted them and have 3 plants about a foot tall in a 15 gallon planter. The soil is 70% tree compost and 30% Black Kow manure compost. I plan on eating the very young pumpkins in the manner of summer squash, but may let 1 of them mature so I'll have seed for next year. The three plants look very healthy although a few of the leaves got tagged by small hail in the last rainstorm. I just thought to give an update since the first post.

BTW, I am interested in soil amendments like rock powders , sea minerals, and kelp. I didn't have any rock powders, but I have been adding trace minerals originating in Great Salt Lake with the sodium removed, about 30 drops to the gallon of irrgation water. Forty drops would be the equivalent of 1/2 cup seawater (without the sodium). I decided to try this after I learned about the record harvests some farmers have had in tsunami areas where the inland was flooded with seawater. Apparently enough rain fell so that much of the sodium was washed away.