1. Why would there be an issue with someone assisting you in constructing a sukkah?
2. While a 10-tefachim-high sukkah is technically valid, is it really useable? Someone of average height could sit on the ground, but you couldn’t do most of the normal activities associated with “leisheiv basuccah” (dwelling in the sukkah), unless you’re accustomed to living in a house with a 10-tefachim-high ceiling.