Having had some experience with all this from any number of angles, let me say:
1) Labels are unlikely to give you digital distribution rights in many cases, particularly if there is no physical product. When they do, they will often restrict these to lossless formats.
2) The sort of stuff you're talking about is far far far far more likely to be purchased on physical media than on downloads.
3) The publishing aspect is dead easy, don't worry about that. I'm happy to give advice if you need it. Basically, all you really need to do is provide notice and then pay royalties as you collect them.
4) It is &really* hard for an outfit without a track record to get any sort of license from a major. And when you can, they will frequently ask for far more than they would ask for if you were established . . . generally to the point where it would be a guaranteed money loser no matter what how you went about it.
5) The wisest thing to do would be to license directly from bands or smaller, quasi-defunct labels who may still hold rights. Once you have a track record of that, things would get easier with the majors. I'd love to see the first Win album on CD again as much as anyone, but Virgin won't even license it to Cherry Red or anyone else, it seems. Plenty have tried. Some of that inaction defies most forms of common sense.
6) One cost that labels don't factor in is the 'vault search' - labels frequently won't license something unless it's from the masters, and when they can't find masters (which happens often), they have to do a vault search. You pay for this, and there's no guarantee of success.
7) Most major labels will not license to you if you're doing something like a Kickstarter campaign to raise funds - be forewarned.
Bandcamp is a way better forum than CD Baby for sales.
9) What you're talking about doing equates to 'premium' releases - charge more. $20 a CD direct sales is perfectly reasonable. Anyone buying deep catalog like this stuff isn't going to be deterred by an extra $5, believe me. And a lower price will not attract more buyers. You're doing the public a special service, act like it!
10) Despite what someone wrote, there are plenty of CDs going for $100 which wouldn't sell 50 copies if reissued. At this stage of the game, prices raise and fall in odd ways. Don't let that be much of a determination in what you release.
11) Start sorting out distribution avenues now. They are sometimes slow to respond to enquiries and to take on new clientele.
Good luck!