yea, your gmail account is your google account. and despite what you've heard negatively about gmail mobile, its actually very nice. no need to pinch n zoom, though I'm a pro at it lol. However, I can't see sent mail.
google is beneficial because you can sync numerous apps together through google. as well as pics and journals and documents and spreadsheets and videos. you name it. That's a big reason why it's cool. It syncs, and stores in the free cloud. So many of the most popular and best quality apps are trying to provide google syncing. I have 4 calendar apps and 2 task apps, and what goes on one calender app nearly instantly appears on all the others. as well as tasks. you have google docs, google goggles, google EVERYTHING. It's the best I see so far....google. I'm most impressed by their free navigation. if you set the settings just right, It's just ****ing amazing. google navigation. ftw