You can download the amazon app store as an apk, they have a free app-of-the-day--usually crap 99% of the time, but occasionally they have some good ones for free. You can sideload apk's, but you do run the risk of installing something corrupted. As a general rule for downloading apps within the Play store, only download things with like, 10,000+ downloads. Obscure ones might be a little fishy.
I've had my N7 for almost 2 months now, so I'd recommend doing the following if you're a newbie:
Download Flash
-Follow the tutorial and sideload the apk from here:
http://forums.androidcentral.com/go...rum/189897-no-flash-got-you-down-try-fix.html
-Download a browser that supports HD flash, for optimal quality. I use xScope, but I hear that Dolphin and Boat are great too.
Good Apps for Optimized Tablet Use
-A screen filter app:
https://forums.androidcentral.com/e...om.haxor&feature=search_result&token=CFjYIt6v, to dim the screen beyond the min.
-This app:
https://forums.androidcentral.com/e...pps/details?id=com.painless.pc&token=O8qmBBB5 allows you to add basic toggles (wifi, gps, etc) to your notifications window, which you can access just by dragging down; this way, you don't need to exit your current window just to to turn wifi off, dim the screen, etc.
-If you want a customizable text clock widget, download
https://forums.androidcentral.com/e...d=in.vineetsirohi.customwidget&token=60-ue8E9
-It's always good to have an HD Widgets app, for your clock/weather widgets. Popular ones include HD Widgets and Beautiful Widgets
-If you feel that the stock launcher doesn't offer enough customization, download something like Nova Launcher Prime--things like app drawers, widget overlaying, altering the desktop grid, etc, aren't necessary but are nice little extras.
If for some reason you want your N7 to function as your GPS, dl a cheap navigation app:
https://forums.androidcentral.com/e...lk.copilot.namarket.premiumusa&token=quGZhg5t which has offline POI's. Stock navigation is pretty sluggish without wifi, at least for me. This:
http://www.amazon.com/gp/product/B0...ag=hawk-future-20&ascsubtag=UUacUvbUpU2279202 seems to work well as a mount.
Pocket:
https://forums.androidcentral.com/e...com.ideashower.readitlater.pro&token=yYHpCiLq is useful for saving articles to read later (since it's wifi-only, definitely comes in handy). Evernote:
https://forums.androidcentral.com/e...e/apps/details?id=com.evernote&token=e-t0N9w0 is just great to have. Anyway, those are some basic tips. Just search online for "best apps for nexus 7" or "nexus 7 tutorial" or something like that.