Hello,
yes 75 is relatively hot, but not too bad, if it goes above 85 then that's an issue, since it will start throttling at that point and if it goes beyond that it can shutoff.
will your laptop die? don't know, depends how hard you overheat it, if the temps stay in 75 range you will be ok I think.
as far as upgrades, GPU - no, RAM - yes.