All of his LR lessons use questions from before PT36 as practice with explanation videos, and there are more practice sets with each package upgrade... so if you're looking for some, thats where you can find them :D
... only paying the difference to upgrade to Premium and/or Ultimate ... in a course, can I upgrade later?
Yup. You can ... upgrade to a more extensive course ... the two courses. When you upgrade a course, from Starter to ...