Doing one park each day is completely normal. That would be 4 days.
This is a good idea. Try not to book too much on arrival day or on departure day.
It can feel like “losing” out on experiences by not filling those days with activities. However, IME, with a “mixed” group everyone is going to need a day to settle in and “Start” having fun. Then there’s no need to add any stress to a departure day with cramming in activities
If you can time it after Easter and before schools get out for summer you’ll have lower crowds. I understand that may not be possible with so many school aged children.
October is another good time to visit for lower crowds, but you’ll be in the later part of hurricane season. It will rain most days in spurts. However, you get all the great MNSSHP activities and decor!
Don’t plan on more than one TS per day. Personally, I don’t even plan one every day. You’ll find how quickly you get stuffed at the parks. The portions at meals tend to be really big.
A lot of days I prefer to do QS for all my meals. I will look at a lot of QS menus before I go to know my options though! (Especially if there’s a food festival or event like MNSSHP!)
I know you are asking which to avoid, but it does sound like you WANT to go to the rides that make you sick!! 
Here’s a thread dedicated to this!
GotG - Cosmic Rewind. (TL;DR = It’s a VERY fast modern version of Space Mountain. It’s an best Disney coaster anywhere)
Honorable Mentions - 7 Dwarfs Mine Train / Tron / Tower of Terror