I'm interested in both US and EU patents.
I can only speak regarding the US patent system.
Does the patent become abandoned? Yes, see the rules on Notice of Allowance. The issue fee is due within three months of receiving the notice of allowance. If the issue fee is not paid, you simply abandon the application.
If yes, can I revive it? Under what conditions? No, see the MPEP Sec. 711. There may be some exceptions for "expressly" abandoned applications, but not paying a fee is the quickest way to lose your application.
Is it any different if I didn't pay the maintenance fee? Missed maintenance fee payments lead to to the patent "expiring" rather than an abandonment--same result (no protection) but "expired" implies it was valid for awhile, whereas an abandoned application was never a valid patent.
Do I get any protection from such a patent? No.
Is the patent published? I'm not sure what you are asking because the patent application should typically already be published before your notice of allowance. Unless you tell the patent office not to publish your application, it will publish 18 months after you file (or after your priority date, whichever is earlier) MPEP Sec. 1120. With the typical patent application process taking much longer than 2 years, it should be published.
Does the patent block other people from patenting the same idea? Yes and no. To back up the discussion a little, patentability is not dependent on whether someone already owns a patent. So you can block someone from patenting your idea without filing a patent. The easiest way might be to publish your idea and then wait a year, after which your published method, device, etc. would become "prior art" and would prevent someone from patenting that thing. Of course you are taking a risk that someone might see your published idea within that first year and run to the patent office. Limiting our discussion to post America Invents Act ("AIA", passed in 2012), where we are now in a "first to file" jurisdiction, someone could probably do just that and "steal" your idea quite legally. But perhaps you are trying to file a patent (be the "first to file") and then intentionally abandon your application so as to save yourself a little money (by not pursuing the application all the way) whilst blocking others from patenting the idea. I don't know why you would do that because it is an awfully lot of money and trouble just to file a patent (see the USPTO fee schedule, not to mention attorney's fees), but I suppose you could and perhaps you might even succeed. Yet I doubt anyone really "games" the patent system in such a manner and gets away with it. There are loopholes within loopholes within the MPEP, and the USPTO has a lot of discretion in examining an application, so you might find yourself spending several years and thousands of dollars only to find someone with a VERY similar invention who successfully obtains a patent despite your best efforts. The advice, in short, is that if your invention is good enough then find a lawyer and actually obtain a patent.
Good luck.
You can actually still revive an patent that has been abandoned for non payment of an Issue Fee. We have done it several times, and are going to do it again now. Of course, the petition fee to revive is expensive.
Also, yes your application can block someone else from patenting the same exact idea if it has been published. Anything can be prior art, a website, an expired patent, an abandoned application etc. However, it does not block someone else from making or distributing your idea.
