Allright heres the case.
i see alot of ps1 games in psn that requires (ps3/psp) and i know that all the psp games work on the vita but does the same go for ps1 games??!?!
First of all, NOT all PSP games work on the Vita. In fact, there is only about 40.
At the moment, NO ps1 games work with the Vita. Besides through Remote Play. They all work like that.
Actually, only a fraction of PSP games work on the PS Vita (about 275 out of like over 1000 games), although most blockbuster PSP games have made it to that list. As for PS1 games, none of them can be downloaded to the system. In order to play PS1 games on the PS Vita, you must use the Remote Play feature.
No currently PSone classic do not work on the Vita. However Sony has already stated that they are working on it and should have it running soon after launch. What that time frame is I have no idea but I wouldn't be surprised to see it in the next major firmware update; perhaps maybe version 1.7.
YES, You can play PS1 games on the Vita via Remote Play. All PS1 games are available through Remote Play. As of right now, Pixel Junk Monsters and Encore are the only PS3 games available to play via Remote Play and No PSP games are available through Remote Play. However, if you download a PSP game on your PS3 which you have bought previously through the Store you can transfer over the file to your Vita from your PS3, this is how I have LittleBigPlanet PSP on my Vita and it is not available in Vita PS Store.