Double the filling portion of the recipe if you want a filling-heavy tart.
Pie tart pans vary in size, typically 9-12 inches. You can use any sized pan that you have, but the crust will be either thicker or thinner and cook time of the crust will vary slightly.
You can use just the cherry pie filling, just fresh cherries, or both. Fresh cherries will be more tart than the pie filling and not give you a swirl. You can get a cherry pitter online here!