If you think you want more memory capacity, then do that over speed and timing, 5000 still cares about timing and speed but less so than your 2nd gen, rn is an excellent time for memory prices, so i would certainly recommend another 16gb (I'm assuming you already have 2x8) if you think it would benefit your dev work you could go 2 x 32gb and sell your old 2x8(not for much... but its something)
why do you want an AIO, it probably wont perform better and its more work and worry...
No, keep the chipset. if you don't have a feature in mind you don't need the new chipset.
also i think the used 3080 would be a way better value than the 4070, keep the budget for more or faster memory.