There are some free downloadable games, yes, but the PSN is mostly a store to purchase digital versions of games.
Yes, the PSVita has physical games, small cartridges called PSVita Game Cards. The PSVita has a slot at the top for them.
Yes, the Youtube app for PSVita is free.
There are many games that are downloadable on free pc games downoad sites. You have for example Bomer Mario, Alien shooter, Crazy birds and also City Racing.
The PSVita is not region locked, a US PSVita can play an EU PSVita game as would be bought in the UK.
There are many places where one can go to find free downloadable PC games. Many gaming sites have an abundance of downloadable PC games. The Microsoft website also has many downloadable PC games.
The PSVita does not use UMDs, your games either come on the new PSVita Game Cards, or are downloaded from the PSN.
You don't need to, PSVita games are downloaded straight from the PSN.
yes
Playstation Plus subscribers get 'free' games each month, which they can play for as long as they hold an active subscription. There are a few free games already on the PSN but nothing particularly great.
Gamehouse is a website providing full version of downloadable games for free. They also have game boards giving access for PC, Mac, online, and mobile game users.
One can search for free downloadable games at many gaming websites such as Shockwave, Big Fish Games, Pogo, and Gametop. Always remember to only download from reputable sites and to check all downloads for spyware or viruses.
You should try ROM husler.