The rating is 1000 hours at 105°C continuous. I don't think it matters if that 1000 hours is broken up, but any hours at 95°C also counts against that 1000 hours as well as hours spent at 30°C though much less than that at 95°C. Plus this is all statistical, so there's no guarantee they will fail at exactly 1000 hours at 105°C.

Ripple current induced heating is likely more of a concern as there's no thermal insulation from the source of the heat - it's heating itself....

cut off is for preventing overcharge?

It depends on what battery chemistry you selected?

14.4V seems like a sealed lead acid (allowing for some equalization) or lithium iron phosphate (full 100% charge). I think the thresholds should be different for lithium iron phosphate versus cobalt or manganese which is not clear in the description, but suspecting it's iron phosphate because there is no really good multiple for the cobalt/manganese cells (4.2x4 is too high and 3.7x3 is too low)

A 24V pack usually means cutoff at 28.8V.