It had always been my hope that Bajor wouldn't join the Federation. I thought they should take their place at the "grown up's table" and stand next to the Federation and Klingons as equals. I kind of saw them as Britain during the Cold War, maybe they didn't have the poplulation or large territory of the US or Soviets but they could definitley hit above their weight.
The Bajorans were very proud and capable people. It just kind of seemed almost sad to me that, after decades of Cardassian rule, they would just be gobbled up by the Federation without even attempting to try it on their own.

Um...don't mind me. Just thinking out loud again

Kira Nerys felt the same way about Bajor and the Federation. She resented that after decades of tyranny and cruelty by the Cardassians, the first thing the Bajoran provisional government did after the Cardissians finally withdrew was petition for membership in the Federation.

She felt at the time the Bajorans didn't need the Federation's help--after all, the Cardassian occupation began with Cardassia extending "help" to the Bajora. In her eyes, Bajor was simply trading one extremely powerful master for another.

It was actually Captain Sisko who derailed Bajor's initial admission into the Federation in the months prior to the Dominion War. Had Bajor become a Federation member world, the Dominion would have mercilessly conquered the planet. But by still being technically an independent world, Bajor was able to sign a non-agression pact with the Dominion and avoid hostilities with them.

In the post-Dominion War era, we don't exactly know (or perhaps ever will know) whether or not Bajor actually did eventually join the Federation, but it is believed that by this time--2380--Bajor has finally been restored to a pre-Cardassian occupation status.

Bajor may very well become simply an ally to the Federation the same way the Ferengi eventually did...

Were there any references to Bajor's status before the occupation, which I guess would've begun around the TOS movie period? Did they pretty much keep to themselves? Or is it something they've never really talked about?

The first onscreen mention of the Bajorans--also known as the Bajora--wasn't until the fifth season TNG episode "Ensign Ro."

But historically, the Federation may have known about the Cardassian occupation of Bajor since the 2340s--probably during the time of the Enterprise-C (the time of initial hostilities between the Federation and the Cardassian Union).

There hasn't been any onscreen evidence of Federation contact with Bajor prior to the Cardassian takeover. But there is mention of the Bajorans having rudimentary space travel during the 16th-Century.

From that, you can speculate that the Federation may have at least known about Bajor during the time of TOS--if not actually ENT--but did not intervene in the Cardassian invasion and subsequent occupation...

I always thought that Bajor had been more of an isolationist type of people, who even though they had the abilities to go where no one had gone before, they didn't really care.

Then they had the occupation, that changed their entire way of life.

I have always thought that if we went back to DS9 after Nemesis, we would find that Bajor had finally joined the Federation, with Captain Kira in charge of the station.

I don't know how "official" it is, but in the June 1999 issue of Star Trek The Magazine it says that "the planet has to choose it's council members and the local militia must be absorbed into Starfleet."