I didn't see any info in this FAQ on how to extract or backup apks you already have installed to your SD card. I'd recommend Astro File Manager for that (free in market). I also didn't see any info in this FAQ about sideloading apps without needing a root. Here are the steps I use:
How to sideload an apk:
Original link here, but I've provided my detailed noob friendly steps.
http://forum.androidcentral.com/show...589#post236589
1) Download and extract Android Central Sideload Wonder Machine:
http://images.androidcentral.com/sit...C-SWM-v1.0.zip
2) On your phone, go to settings->applications->development and check the box that says USB debugging
3) Connect your phone to a PC and select "Charge only" on the phone. Let the drivers install on the PC.
4) Launch "AndroidCentral-SWM" (this is in the Sideload app folder you downloaded and extracted)
5) Click "Choose a File"
6) Browse for the "xx.apk" that you want to install and hit Open. Click OK on popup, hit Go and follow prompts.