We are currently building out a Q&A tab for each property, where Buyers can ask questions for the Sellers. For now, be sure to also check the 'Public Notes' tab to see if there are any notes contained there that may provide some information about the listing.
Also, once you make an offer, a "CHAT" tool opens up, similar to IOS iMessage, which you can then use to communicate. You can read more about this feature HERE.
Until we get the Q&A feature implemented, and in the case where you want more information before making a serious offer, you can make a nominal offer and tell the Seller (in the Subject to Line) you are making this offer to enable the chat tool and ask for details from the Seller.
Below is a screenshot depicting our suggestion for this use case.