can i go retrieve the dragonstone return it and buy the breezehome. and call it good on main querst? or is that the point of no return so to speak?

I believe once you retrieve the dragon stone you come back to whiterun and a dragon attacks. Once you defeat the dragon you can buy Breezehome. Although if you don't want the title of dragonborn don't speak to the jarl and go straight to Preventeous after you kill the dragon and he should give you the option to buy Breezehome without everyone in the world knowing you are the dragonborn.

what i ,eant if i wanted to go adventuring without dragons popping up everywhere and without finishing the main storyline

The quest (Dragon Rising) that causes the first dragon to attack Whiterun - and that also leads to them appearing elsewhere - is triggered when you give the Dragonstone to Farengar.

You can have it for as long as you like, just don't go back to talk to him after you get it. He will want it and I've heard (not personally confirmed) that once he asks for it, you don't get any other option except giving it to him then and there. I suppose it could be possible to "Tab out" of the conversation without answering, but I'm not sure.

According to UESP, you have to complete the Bleak Falls Barrow quest before you will be allowed to buy property in Whiterun, and completing that quest includes giving Farengar the Dragonstone. So I don't think you can get Breezehome without triggering Dragon Rising.

I didn't get any random attacks when I had A Blade in the Dark in my journal, but hadn't done any of it. When I wandered too near a Word Wall the corresponding dragon would attack, but I had no true randoms.

What happens if you don't follow the others to kill the dragon, then? Will they kill it anyway, or will they just be standing there by the watchtower, forever waiting?

Are the random dragons triggered when Dragon Rising is complete, or when it has started?

It seems like the dragon doesn't show up until you enter the tower.

I played all the way up to (not completed - I didn't meet with Delphine) A Blade in the Dark on my 2nd character and didn't get a single random attack. If I got too close to a Word Wall the corresponding dragon would attack, but I didn't get any randoms.

I read somewhere i google it and i heard from a friend that dragons dont start appearing until after a blade in the dark. the first one is only there so you can find out your dragonborn. the next two quest are related in theory to learning bout dragonborn

i did the thing with delaying A Blade In The Dark, and IIRC the only dragon trouble I had was with one flying around southern Eastmarch. That one does have a Word Wall so technically it's not a "random" encounter. However I didn't have to do much besides cross the river into that part of Eastmarch to precipitate an attack. The closest I ever got without him attacking was the Hagraven's shack in Witchmist Grove, and that was by going way north and backtracking so I never got any closer to him than necessary. Even then I was shaking in my boots the whole time because I could hear him roaring off in the distance and see him circling around beyond the trees.

I really hoped that delaying that quest would mean that Alduin didn't raise any dragons at all, but either he does it offscreen while you're putzing around or there are more living dragons who come out of hiding after Dragon Rising and never had to be raised to begin with.

Breezehome is not that good of a home, I don't know if I would risk Dragon Attacks for that home (if your goal is to avoid the MQ).

Precisely. I delivered the Dragonstone, talked to everyone about going to the western watch tower, and then never went for 6 levels or so. No dragons.

Just now went to the watch tower and there before my very eyes was a freakin' dragon.

Party don't start til the Dovahkiin gets there, amirite?