Maximum RAM in an Amiga 2000??

[amigaksi]

... just without the benefit of being chip RAM...

Maybe a bit of basic knowledge helps here: the Amiga system architecture is divided into two parts: the CPU part and the chipset part. Both can work independently from each other. On a single bus, only one device at a time can be active.

So the CPU can read/run code/data from the ROMs or  - if present - true fast RAM while simultaneously Agnus is e.g. shovelling bitplane data into Denise or the Blitter's shifting bits around. When the CPU needs to access the chip side, the busses need to be connected (asynchronous CPU boards require synchronization here) and the CPU must wait for a free cycle to use, effectively slowing it down.

On the CPU side are: CPU, ROMs, CIAs, fast RAM and on the chip side it's the famous DMA architecture sporting graphics, sound, floppy - all within chip RAM and controlled by Agnus.

If you don't have an accelerator (default condition for A500/A2000), then fast ram is still being accessed at same speed as chip RAM so I guess it's just "fast" because there's no DMA cycles getting in the way.

Now, slow fast RAM is memory that exists on the chipset side, but due to architecture limitations, it's not usable as chip RAM. But since the CPU needs to connect to the chipset side it's just as slow as chip RAM.

And that's the dark side of the force.

[amigaksi]

Nothing special, since a single CPU cycle consists of two bus cycles.

There's some timing map in the HRM that has the memory cycles as being same as color clock cycles (3.58Mhz) which means 2 cycles of the 7.16Mhz crystal.  Move.w D0,D1 or NOP instruction is 4 cycles since it's 2 cycles for fetch and 2 cycles of internal operation when bus is free.  So I guess you meant the reverse.