Does the psp 3000 come updated with version 5.50?

no, if u buy a new one and not a used one. it will start with the earliest update if u buy a new one.but if u buy a used one it depends on wut the last person who owned it put on the psp.and yes u can tell the difference because i have a 3000 and my friend has a 2000. for ur middle question there is no way to downgrade it that i know of yet. but im prettysure they are working on that and im pretty sure they are working on making a chickHEN for 5.50.