The latest PSP update was 6.37
It's version 6.37
Probably 'cause you already have the latest version
Download the latest update, and redownload the games from the PSN.
It depends on the game. If the game needs the latest firmware, it can't be game shared to a PSP without that update.
Some games need the latest update, you should update the firmware to the latest version.
If you try to connect to the PlayStation Network with an old firmware version, it should give you details on how to upgrade to the latest version.
There are five versions of the PSP, the original PSP, the second one is PSP Slim and Lite, then PSP-3000, next was the PSP-Go, and the latest is the 'Street' PSP, a budget model released in Europe. The evolution of the PSP has been rapid and it is still widely used by gamers.
Yes, in fact, subway surfer can run in psp as long as one has the latest version of psp. Otherwise, the subway surfer game will be slow and also a bit glitchy.
You need the latest version to be able to access the PSN, so just update to the latest, it won't affect your ability to use UMD games.
PSP 300 or PSPgo
The psp touch
the latest price of psp go is 17000