Hey @Brett Kash I can answer a few of these questions.
1. Letter and postcards both have their place. If you have a niche list of fewer than 1000 leads I will always recommend letters. Postcards are really good for high quantity because they are less expensive and you can get in front of more people at a lower cost. If you have a more niche list then you should send letters. They are more sturdy and tend to get a better response rate so it is worth the price. ***Tip: You can also try a Trifiold flyer if you want to test a mailer that is really unique as well.
2. This depends on your market and your company goals and strategy. If you want criteria templates I can send you some separately but it will depend on what your goals are.
3. There are a lot of options. One go to would be listsource. You can also drive for dollars or pull from public records to get lists.
4. Depends on budget but I would say you want to base this number on what you can mail to consistently for at least 5 to 6 touches. I wouldn't start with anything less than 500.
I would be happy to discuss more if you want to message me or give me a call.
Cheers!