Im really new at coding so I hope im not asking silly questions....

How do I set which pin is for output?
If I have 18 pots connected, only a max of 16 will be used for the PPM stream. If I only want say 11 or 12 channels in the PPM stream, can I set which pins are used for the PPM stream? How?
In PulsePosition.h it references Arduino.h, Im not sure how to include this or what its for.

Now for a bit of an extra question;
Eventually I want to have a windows GUI to create different models for the PPM library. I will communicate by bluetooth.
(What I mean by this is to have different settings files that specify which pots do different things, or assigned to a different channel in the PPM stream)
Generally speaking RC hobbyists use different settings for different models, so as I switch from 1 model to another (say from a plane to a multirotor), I'd like to be able to choose the correct settings from within my GUI.
I'd like to build each "model" settings file from the GUI, but embedded within the teensy. That way I can switch from one windows tablet to the next without losing the model.

Some other things I'd need to integrate are trim buttons to get the pots centered correctly. The numbers I get from these will need to remain constant in each model.
LEDs that signify which flight mode is selected.
Option for Expo for each channel
PPM input from another controller, and then mixed into my own PPM output.

I guess these will all come along in their own time, I really just want to get the bare PPM stream running first. The key thing I want right now is the best way to set out my files/code so it suits my final product.