For 6
メアリーとたけしは... Mary and Takeshi... (do something jointly).
メアリーはたけしと会う Mary meets (with) Takeshi (に会う is also possible).
You are getting close, though. After the 会って, try "going (in order) to drink coffee" rather than "goes, then drinks coffee".
8.
~をする (in te-iru form) can be used to describe having a physical feature.
9. It's not that you can't use 晩御飯 it's that you can't say 寝ます for "is sleeping". (and the original didn't specify what he was or wasn't eating).
side note: 寝る is "in bed" or at least lying down, 眠る is "eyes closed/unconscious". So you can use the former if someone has "gone to bed" even if you don't know that they're actually sleeping, and the latter if they're napping in a chair.