The "one invitation per day for 30 days" challenge just states that you must invite one (1) woman over to your place per day for 30 consecutive days. This can be a girl on a date; one you meet at a bar; or if you don't have any of those, go do some street approaches and make an invite there. Try to get girls as comfortable as you can, but the point of the exercise is to do the exercise. If you're short on time, pick a girl, approach her, flirt for two minutes, then propose she come to your place.
The exercise gets you comfortable inviting women home. Most guys typically also get at least a few girls who come with them that they did not expect would, which is another thing the exercise does for you (shatters some preconceived notions about how 'ready' a woman has to be to join you at your place).
There aren't any rules beyond that. I'm ambivalent about including online game. If she's seriously coming out for a date and you get her to come straight to your place I think you can count that. If you just message some random chick on Tinder that she should come to your place that doesn't count. It's just too easy to do. The exercise is mostly to get you comfortable doing this in-person, with a flesh-and-blood woman in front of you looking at your eyes, primed to react to you one way or another depending on what you say and how you say it.
Other questions you have here:
2. If it goes nowhere with a girl and she denied you sex, often that is not going to work and it's better to move on. But sometimes you can get her the next time (or a subsequent time!). I thought(?) I had an article on this... maybe I didn't and should do one. But sometimes the girl is clearly into you and just has some reason she is postponing sex, and it can be worthwhile to keep at her a bit to get it (if you like her enough). Just bear in mind you get more attached to her the longer it takes to get to sex (generally).
3. Totally depends. If we were having a conversation and I ask her something important and she suddenly vanishes, I'll wait a few hours and possibly call her that night. If it isn't important I'll just pick up texting her again a few days later. But it's generally not a good sign. Other times I'll just not text her back at all; sometimes it's because I'm like "Meh, don't like her enough to persist if she's being difficult", other times it's because I legitimately just forget about her. Sometimes in those cases the girl will resume the conversation herself; other times we just forget about each other and go our separate ways.
4. Check my forum posts on those subjects. I've linked you to them a bunch of times now so I know you've seen them. Nothing else I have to add on that.
5. Giving up or scaling back goals is a normal thing with age. Imagine if every guy who wanted to conquer the world at 20 was still trying to conquer the world at 60. We'd have a whole lot of petty dictators! So this is okay, so long as you're replacing the goal with something else positive you genuinely want to do. People do not stay constant, and you at 30 will not be the same man you were at 18 -- you have a lot more experiences, many different perspectives, and the world itself has changed, too. It's okay to evolve. Just make sure it's a positive evolution and not just "giving up and replacing it with nothing."
6. Anything can be worth anything depending on circumstances. Sounds like that's a good course for you. You've been worried about women for 6 or 7 years now? But haven't made much progress (at least based on what you report). Women aren't going anywhere; you're a man, and men age well. If you spend a few years to get your life together, and come out of it on the other side more financially secure, more confident, more in-command of your life, you'll come out of it a more attractive man better positioned to improve faster with girls too.
7. Those guys going crazy are mostly all Indian. You're not and I'm not. I didn't get The College Experience and maybe sort of regretted it a little bit for the first few years after school when I wasn't doing that great with girls yet? Once I reached the point where I could get laid consistently with very attractive women and I was able to socialize with cool, successful guys, I did not have any lingering desire to have been whipped in the ass with a fly swatter by my frat bros or to have hooked up with some 10-pounds-overweight drunken freshman sorority girl with blonde highlights at my sticky beer-floored frat house junior year while listening to Bon Jovi at full blast. I mean, have you ever been to the Full Moon Party in Koh Phangon? If I really wanted that experience, I would just move there, or Majjorca, or Pattaya, or Mykonos, or Boracay, or one of those places for a year. I had a friend who lived in Koh Phangon for 8 months and shagged so many women and drank so much alcohol and made so many friends he basically never wanted to talk to another human being after that. He had his fill. I do not think you need The College Experience to be happy in life, unless that really is your One Shot To Have Some Semblance Of Freedom and you are just going straight into the corporate meat grinder after that, where you will climb the ranks to middle management, never taking more than your allotted 2.5 weeks of vacation off per year, marrying your post-wall wife in your mid 30s after you are done hooking up with bar girls and she is done with drunken flings with men she barely remembers, producing your 1.8 children, having your mid-life crisis at 47 where you buy a Porsche and have an affair with an ugly-but-available woman in your office, and getting divored sometime in your 50s after your children have left for college or are just about to. If you're going to go that route (and my guess is most of the guys freaking out about missing out on The College Experience are all going to go that route), then I guess in that case it might really be your One Shot To Have Some Semblance Of Freedom and you maybe want to prioritize doing that. But then again, if that sort of life is so important to you, maybe you should rethink the whole traditional cradle-to-grave grind in the first place? Just thinking out loud here.
8. Pretty sure that's the same as the earlier question. There's not a particularly good way to teach nuanced social calibration over the Internet. So I will say... experiment with "falling back" in different ways, with different women, and see what gets you best results.