The main thing that's been making it difficult for me to start the game again (accidentally broke my character with too much showracemenu) is that I've been wondering what effect Hadvar and Ralof can have on the civil war quest line. I've been extremely indecisive about the entire war (Ulfric is racist and will leave men divided against Thalmor, but I've also heard a lot of stuff about the empire being crippled, and with the final DB quest, I'd probably make it even worse). Anyway, normally I'd just side with Hadvar since that gets me a pile of ingots to work with (the pile under the Riverwood blacksmith's workbench can be taken without stealing if the player befriends Hadvar) but once I finally do decide who I want to side with, I don't want to find that I shot myself in the foot by choosing the wrong starting guy.

And yes, I do know that I'm overthinking this and that I can just play through twice, but I tend to do everything on one character and then lack the motivation to start from scratch, so I want to do things right the first time.

It doesn't matter which escape-buddy you choose, other than getting those ingots for free. You can join the Stormcloaks if you escaped with Hadvar, and vice versa, without any issues.

I have a question... If Rolof saves me, and I become an Imperial.... he will be deleted right? please say he is, I really can't face he after doing this

I know I can join without trouble, I was mainly curious as to whether or not who I save has impact on quest content (as in do they show up later, or do I just kinda forget about them)

No. Nope. Nada.

I'm fairly sure that they'll show up at the Jagged Crown quest at the earliest, no matter if you escaped with them or not.