After jailbreaking IPHONE4 4.2.1, I want to upgrade to 4.3.2 and then jailbreak again. Will the originally downloaded applications disappear or become unusable?

After the assumption fails, your machine will become a white apple.

No failure. There is no chance of losing apps, be sure to back them up before you jailbreak.

After jailbreaking, all applications will be reinstalled, and none of them will disappear. Iop things will disappear, but they can be restored. But some game records are gone. The text messages are gone, the photos are all gone, and they cannot be restored

I hope this helps, thank you.