Oh yes, I do believe that if the Doctor and Jackie were actual friends first (as opposed to simply friendly acquaintances), Jackie would have attempted to school Rose into being more respectful. Not sure it would have worked, though - Rose tends to get worse when it's pointed out to her how horrible she's being.

It'd definitely be an interesting take on series 4, to start with Donna's family actually knowing the Doctor beforehand and being able to help him in Sontaran Stratagem and JE.

I've honestly never thought of a self-insert like that, if only because I have a tendency of writing it so that everything ends up worse rather than better. I seem to really like tragic endings, and well, JE is tragic enough as it is! :)