My brother was supposed to join us yesterday (would have been his first time) but couldn't make it. Looking back on our morning, I would say it's actually pretty doable if you do it in the right order.
First to note is that we were allowed into the park and down the Starway before the 8am early entry began, so get there early. When we walked in, Mario Kart was posted at a 30 minute wait, Toadstool had no line and neither did the games. We went for Mario Kart's standby queue first (which only ended up being like a 15 or 20 minute wait). Then went to Toadstools. Then the park opened and the lines for the cafe' and games got crazy (except for Thwomps for some reason.. maybe folks don't know it's hidden in there, not helped by the Toadstool line hiding it).
So if you go in right at the start of early entry and hop from game, to game, to game, to game and head to Toadstools, I think you could make it work. Characters weren't out because of the rain so I can't speak to how long their lines would have been. But Mario Kart's queue is sort of obnoxious because of the videos you are forced to watch in the video rooms so I don't think I would risk trying to work that into your early entry.. unless you want to use Single Rider.
The absolute greatest part of the Single Rider queue is skipping all the videos you're forced to watch so if you utilized it and your group doesn't mind hustling, I think you'd be safe.
So maybe: enter -> games -> single rider Mario Kart -> Toadstool Cafe'?
Whatever you do, do the cafe' last in your hour. The time it takes to order, be seated and wait for your food will otherwise totally drain your extra hour. I wish I could speak to the character interactions but they weren't offered yesterday, sorry.