Answer #1, yes I've used a ZorRAM and a BigRam+ in A4000T & D's (even an A3000D) and they work fine. When used with a Mediator (which can grab 512 MB of Z3 address space) one has to be careful with the way the Z3 address space (1 GB) is allocated; if you do it incorrectly you will run out of address space. For example, the ZorRAM 128MB allocates 256 MB of space thus wasting 128 MB of address space. The two ram boards are otherwise identical except for the layout: the BigRam+ has all its RAM on 1 side, and only comes in 256 MB (the amount it allocates). Otherwise the parts and firmware are the same.
Answer #2, Sorry 442 or is it 455? Both are Z3 (32-bit boards) and lay outside the Z2 24-bit address space; so a A2000 can't see it.