If the player's already on your DIII recruiting page, you don't have to call him first. You can recruit him right away. And, yes, the efforts stack...i.e. 2 scouting trips is worth more than 1. You don't have to offer them both in the same cycle, however.
If it's a DII player you want, then gvsujulius is correct. Call them one time to find out if they're recruitable. If so , he'll eventually 'drop' to your DIII list and you can recruit him. OR, you can 'pull him down' sooner with enough effort. It's risky, and expensive, and shouldn't be tried unless the player lives near your school.