RedRaz, what do you mean the lid doesn't fit because of the cutouts? *is confused*
Yes, it's usually perfectly okay to add your plants right away. The only time you might not want to is if you have a planted setup already and you don't want to contaminate it with snails and algae. This I learned the hard way. But for you, yup, no need to quarantine.
Kinetic, aww. I'm sorry about your back. Have you tried acupuncture/pressure? Hehe, just watched an episode of Invisible Man last night about acupuncture. Darien threw his back out and went to a bad acupuncturist who used electromagnetic needles to manipulate him into stealing Chinese artifacts.