Wirelessly posted (White and Nerdy)
Good luck with your gps... Not gunna happen.
As for your slacker, any of the new berries have a boatload of memory which make them very fast.
Need I remind you that you need data connection for slacker... That said, here's the phones that I suggest
Bold 9000- gps/wifi
Tour 9630 -gps
Touchscreen doesn't matter if you are just using it for music. These devices are all running 4.6 or higher and have a bunch of ram(free file) to use for multitasking,music,etc.