Never did the Civil War quests. I would like to do this once. Problem is, I like the Jarl in Whiterun (Bulgruf I think his name is, spelt wrong I know.) and the Jarl in Morthal (I forget her name, haven't played in almost a 6 months now.)

So can I side with the Stormcloaks and still have these Jarls? I think I have to do the Imperial side if I want these Jarls still but wondering if I can start with the Imperials do the quests to keep the Jarls and then switch sides later. If so, how?

If not then I don't know if I will do the Civil War quests just because I like these Jarls but wondering how are the Jarls that replace them.

Nope, if you do it for the Stormcloaks both Balgruuf and Idgrod will be gone no matter what you do.

Balgruuf is replaced by "When the Empire surrendered to the Aldmeri Dominion, they shamed us all..." (Vignar Grey-Mane if that hasn't line been drilled into your skull yet every time you pass by him.) and Idgrod is replaced by some lady from a nearby mine who apparently is only in it for power.