If you go to certain places solo or with a different companion that trigger specific companion dialogue for personal quests AND then go back again later with the right companion will that dialogue still trigger?

Example: I took nelson back with the ncr with raul as my companion. If I go back with veronica will it trigger the dialogue to do one of her personal quests. Same thing with boone...I did a lot of his dialogue requirements earlier in the game either solo or with someone else so am I screwed now?

No idea. It's highly irregular in my experience. I got ED-E and Boone working like they were supposed to (I think), but Veronica doesn't trigger anything and I only had to take Gannon to the Silver Rush and he spilled his guts. Though this may be because it was during the finals quests of the game.