Is it possible to run the XMB (original psp menu) from JPCSP? +question on vid too..

[Hykem]

as the title says - is it possible to make JPCSP behave like the real hardware and load something which will replace the flash memory a PSP uses to load the XMB and.. load it?

Not really...
Also, the PSP's XMB is proprietary, so it would be illegal anyway.

another question - the closed source, commercial video Codec Sony created
that is used in UMD videos - do you ever plan to implement it in the emu?

You mean the .mps files? I have no idea about the status of investigation on that format, but I think it's not decodable yet.