Hi,
so: first stop is to watch all the videos and screencasts from the playmaker website and also the various videos on this forums. then study carefully the samples provided, this will certainly answer a lot of your initial questions.
Then, you'll be more confident using custom actions ( they are the same as standard actoins in terms of usage, they just do different things).
If you still struggle, just drop a line here, and I'll get more in details.
Bye,
Jean