[PD] multiple patches

Right now I've just started figuring out pd and writing a few patches and abstractions. But I'm wondering if I waste a lot of time because I can't see the bigger picture. I'm planning on connecting a few more (4-6 in all) keyboards via USB to my laptop running pd. So...

1. Would it be better to run multiple instances of pd or only one

instance? How is the midi input best handled from 6 keyboards? If they all are connected via USB they will show up (I suppose) as different input devices, but is that possible to redirect to different patches running at the same time?

2. How does program change work in pd? Would it be neccesary to write a

specific input module to handle stuff like that?

3. Is it possible to load/unload patches dynamically from pd, for

instance using program change?