Yeah, I took the bus from Pop to PI once, because I wanted to have a Kungaloosh and didn't want to drive back after imbibing - 50 minutes from the time I got to the bus stop till I stepped off at the PI stop:
20 mins wait time
10 mins load time
10 mins drive time to Marketplace
10 mins wait time
2 mins drive time to PI
I guess I could have walked from Marketplace to PI, but it would not have taken any less time than waitig for the bus. And it was a hot, humid night, so I didnt' want to get to PI all sweaty and tired.
Every time I think of that night, it makes me wish I could afford to stay on-site at Uni - everything is in walking distance or water taxi service - but even with Passholder discounts the Uni resorts are out of my price range.
Let me bring this back to the original thread topic, or at least in the ballpark: once you get to Universal, you park in one of the huge garages and walk into CityWalk. At CityWalk, you can go right to visit USF or left to visit IOA. If you go straight, you come to the waters edge, where there are water taxis to go to any of the Uni resorts. No interior driving will be needed at Uni.
While there, be sure to try some of the restaurants in CityWalk and the resorts. I'm particularly fond of an Asian restaurant called the Islands Dining Hall at Royal Pacific resort; it's one of the best restaurants I've tried in Orlando. I also enjoy Jummy Buffets Margaritaville at CityWalk. For lunch I will sometimes go to Lombards, in the Amity section of USF; it's not only excellent, but very reasonably priced for a table service place inside the park, and not usually very crowded.