I have the older 6.0.5. Looks like I'm way behind the newer version, and will need to download the 10.0.2. Will I still be able to access all of my own recordings after downloading the new version?
Yes, the newest GarageBand can open the projects from GarageBand 6.0.5.
GarageBand 10.0.2 is very different from GarageBand 6.0.5, it is more like a light version of Logic. It brings new features like drummers and arpeggiators, but dropped other importaant features like podcasts or the sound effect instrument. So you will want to keep both versions installed.
When you upgrade to 10.0.2, the installer will move your current 6.0.5 to a subfolder of Applications. On no account delete it, until you are perfectly happy with the new version. I am still starting my projects in GarageBand 6.0.5, set everything up with the easy to use GB '11 interface, and then add the finishing touches, drummers etc., in GarageBand 10.0.
Note: GarageBand 10.0 is free, but it is not a full version; you will have to make an in-app purchase to get lessons, instruments, loops. With GB '11 still installed, this should be free. See this document: Expanding GarageBand for Mac (v10.0) content with an in-app purchase