I think OP is looking for where do people usually made trade offers, it's self-explanatory imo. Not necessarily listing new platforms, just asking where do people usually post their ads, which could help him decide which platform he needs to get more inspiration from.

As for the second question, there's really no need to know what platform OP offers, since he's asking whether you're satisfied with your current platform or not, and if you're not, what kind of features you'd like to see to improve your experience. It's like asking "do you like Youtube? What kind of feature you'd like to see on the platform?" etc. In short, he is looking for the weakness of his competitors and sees whether he can use it to his advantage or not.