The iPod touch (not to be anal, but it isn't called the itouch)

is awesome! I've had one since literally, the day it was released. I pre-ordered from Apple.
I have an iMac, and the integration, as you'd expect, with iTunes, iPod touch and the iMac is awesome. It's not quite as smooth with a Windows machine, but nothing that you'll notice if you'll only use Windows with it.
You can download any apps you want and they will be housed in iTunes until you connect your iPod to your computer. You can't use apps on your computer, only on the iPod. It's actually a great opportunity to browse through and find apps that appeal to you. Same goes for any music you want to purchase and have on-hand for when the day comes!
I rarely pay for apps. There are so many free ones, buying apps is hardly even necessary. My favourite one, and it's free too, is "Remote". It actually turns your iPod touch into a remote control for your iTunes! You can browse, play, pause your music/movies/tv shows/podcasts etc almost the same as if you were sitting at your computer. Definitely look into it. The cool thing with the free apps is just download any you even think you'll like, and if you end up not caring for them, you can simply delete them. Nothing lost.