I believe that Lightfoot owns the rights to all of his songs since 1970 or 1971. Not sure what happened once "Waiting For You" came out though. I know that he started his own cover around the time "Sit Down Young Stranger" was released. All the songs in the '70's and '80's belong to Lightfoot. I may be making some assumptions here, but I'm pretty sure this is the case.
I am 99.9% certain that he does not have rights to anything prior to '70 or '71.
Everything is negotiable as far as rights go in regards to the artist and the label. What is not negotiable is the amount that must be repaid to the label to cover costs. Being that Lightfoot has been so successful for so long, he really brings a lot to the bargaining table, in my opinion.
I don't think that Lightfoot made the decision to leave Warner and be without a label. It sounds like once "Painter" was finished, the decision rested with Warner with what they wanted to do with him.
It costs a certain amount to make the CD. Typically, the artist will see no money until all monies are recouped from the production. This is where I think Lightfoot may have some say, because of who he is. Not with how soon he gets paid, but how much. The key is how many copies are sold within a certain time frame.
At any rate, when Lighfoot confirms that he can tour again, his new CD will be much more attractive to a label. I really hope he goes with Oh Boy. Moreover, I really hope his health keeps improving so he can enjoy the rest of his life, whatever he chooses to do with it. I just hope that touring is at least a small portion of it.