Cutting always slows growth, but it can be used to generate lower branches if desired. If you're not looking to make small trees, there's no need to cut.
I'd guess there will be another repot before 5 years are up, if only because the colanders often degrade after the 2nd year. I usually move the trees into larger colanders after a year or two. Alternatively, you can leave the trees in the small colander and place tree and pot in a larger colander for faster growth.