Develop a bare lot, but with what and how

[Account Closed]

I have identified 2 separate lots in Marysville Washington (Snohomish County) that are bare and undeveloped. I have not contacted the respective owners (yet). My vision is to develop/ build and have multifamily structures built based on the size of the lot as I see it. (One lot could potentially be commercial/ mixed use due to the proximity of an existing mixed use.) However, I cannot tell what can be built on either lot/ what they are zoned for. One of the lots states undeveloped vacant land and the other states that it is an SFR despite the dwelling having been demolished.

Besides the fact that I need to mail off letters to the owners on record, where do I start for determining the dwelling size and type that could be built? I feel that I should know these things in order to seek finance and outline budget as well as exit strategy (or hold).