gps and themes question pls

[ianton]

hey guys, can u recommend me a good gps for my desire pls? it can be form the android market or even install it via the sd card

and how do i change me theme on the mobile?

and last thing how do i find appp that i must pay for through the market e.g. i wanted to buy angry birds game and when i search it from the market the only versions i find are free and the demo, i never met something that there is pay for it but always free

thanks