Tam, how long are you going to be working in Saudi? Starting an avocado from a seed, IF it can survive the hot temperatures there at all, it still will give you fruit in 5 years at the soonest, and more likely 7 or 8. That's how long it takes here, in pretty much ideal climatic conditions for them. Our high temperatures in summer are usually mid-90's F at most. Very high humidity. Dragon fruit also grows well here, but it needs full sun to make nice fruit, so again a strategic placement and mid-day shade is going to be required for you to grow that.
Mango start easily from seeds - the big pit of the fruit, laid sideways on some soil and kept moist. But again you have the long wait for a tree to get to fruiting size. Maybe not quite as long as the avocado, but close. I'd hate to see you get discouraged by waiting and waiting for those. Then just when they get to a size to fruit you move back to North America? arg.
Stick to annual vegetables and fruits you can start quickly from seed and see a harvest in the same year. Or eggplants and peppers - the peppers should be able to take at least some direct sun at this time of year, and they need it to fruit. Just water them heavily every day (in the morning is best) and fertilize diligently.
How about some melons? They love high temperatures but need a LOT of water to produce good fruit. Um, how much room do you have? Melons are a rambling vine sort of plant but you can support them up of the ground if you need to - an old ladder or some such frame will work well.
