For the DVD to play games you've written to a DVD+R DL with your own burner there is only 1 mod available these days (different versions of it tho) and it's called iXtreme, there was another method before (NME chips) but, it's useless now a days (it doesn't work with the newer games)
The F3 Installer ISO only updates F3, but it doesn't update your actual dashboard/kernel (the xbox 360 dashboard) right now you don't have to update, but in the future you will, when games stop working (new games) or you want to use Title Updates you'll need to update your kernel...
If you're not going to play anything newer then you are currently doing, and not having any particular issues there is no need to update
If you don't have a Xbox 360 Slim (4GB Corona, a.k.a. MMC Corona) xeBuild GUI will identify pretty much all parameters for you as to what you need for it to work (however, you might need the nofcrt patch aswell which it is unable to detect at this time)