I am a software guy that got into wholesaling, so it is not like I've been in the industry for decades, but definitely in your shoes last year.
1. Definitely start in your area. If you can't close deals face to face, you probably won't be able to close deals over the phone. It also helps you build the intuition on how much you can offer. The 70% rule is more like a heuristic, depending on the property you should go lower or higher on the offer. You don't want to miss out on a deal that could make you $30k just because you need to offer 80% ARV.
2 PropStream, PropRadar are great ways to get started. They essentially give you all properties in an area, and you can skip trace and call the homeowners. The best way to think of it would be virtual door knocking. Slim chances of success, but cheap and easy to get started. After that, I would encourage you to go to your county recorders office / court to request data yourself. This is probably the most up to date information you can get, you can get the data cleaned, formatted and skiptraced for pretty cheap using some new comers like GoliathData. List is only as good as the caller, so make sure you have your script ready to go.
3. Becoming good friends with buyers' agents and local investors. In my experience, they have the fastest turnaround time vs folks out of driving distance from the property. If you are listing it online, aren't you just in a sense just "listing it on market"? Your advantage is your connection to the right investors with cash to purchase the property. Another reason why if you cannot operate locally, you probably won't be able to succeed wholesaling remote.