What actually happens between writing down an address and having a contract in driving for dollars?

The address by itself is a note in your phone. The chain from there is short but every link can fail.

First you identify the owner. County assessor or recorder records are usually online and free, and they give you an owner name plus a tax mailing address. If that mailing address is different from the property address, somebody else lives somewhere else and the house may be vacant or inherited. That single comparison is most of the early value of the record search.

Then you make contact, by mail or by phone. If the phone number isn't in the record you pay a skip tracing service to match the name to numbers. Then you have a conversation, and if the owner is willing to talk price you write a purchase agreement.

"Under contract" means a signed purchase agreement with earnest money and a due diligence period that lets you cancel for a stated reason. The small deposit part is real rather than a trick. In distressed off-market deals earnest money is often a few hundred dollars, because a seller who wants certainty cares more about your close date than your deposit.

Since documents are your thing: if you plan to assign the contract to another investor for a fee, the agreement has to permit assignment, which is why people write "and/or assigns" after the buyer name. Several states have added disclosure or registration requirements around assigning residential contracts, so confirm the current rules where you're buying with a local attorney before you rely on that exit. And most logged addresses die at the contact step. A list of 500 might produce a handful of real conversations.