As mentioned previously, in WA, a home that is "pending" means that the seller and a buyer have come to an agreement and the sale is proceeding through escrow to closing. If a home were still going through an inspection contingency you would see "pending inspection" so if a sale is just "pending," they are finished with any inspections. They may or may not still be going through a finance contingency. A pending sale can occasionally fall apart, but the sellers can't actively cancel the contract. If you are interested in making an offer on a property that is pending, you would need to settle for being in a back-up position. I hope that helps!
As mentioned earlier, you will need to check with any local REALTOR for your region's MLS rules. In the Seattle area, if a basement is heated and fully finished, it is included in the total square footage (one of the reasons basement remodels are so popular right now!)