I can remember the house right next to the main stand (think it may have been the one that stopped the full main stand extension) selling stuff like old programmes, so the club must have owned it at some point. Also there was a portacabin outside the main stand which sold a very limited amount of merchandise. In fact I don't even think they sold the kit. My first motherwell shirt was purchased from the sports shop in the town centre.
Then the shop was moved under the stand, just at the entrance to the enclosure underneath the main stand. Also sold tickets.
Your right about preserving the old turnstyle entrances . Shame no one at the club had the fore site to keep them and even move it elsewhere at the ground.