I am 10 days from my first Nexus 7 purchase.
What should be the first 5 apps I secure and install
The Golf Bum
Depends a lot on what you will be using your N7 for:
Watching videos: MX Player
Reading books: Cool Reader
Moving files around your network: ES File Explorer
Reading pdf files: ezPDF Reader
Listening to music, audio books, etc.: Winamp
Reading magazines: Zinio
Listening to the radio: Tune In Radio
Oops. I went over five apps. You could get 50 responses and it is doubtful you would see the same list twice. Instead, I suggest you search for the type of app you want to use, check the reviews hit the Play Store. Most of the apps have a paid and free version. Others have a free testing period. You always can get a Play Store refund by uninstalling within 15 minutes.