It can be used for multiple purposes; it is an auxiliarity track that can be used as a group, as a send effect, automation, routing... Basically everything except holding audio or midi data.
By editing.
Several ways; Cut that single part of the track out and put it on a new track and with the plug in. Automate the bypass on the plug in to only switch on during that part. Make an aux send to the plug in and automate the send to only switch on when that part needs to be on and off the rest of the time.
Yes. I operate Pro Tools M-Powered 7.4.2 with an M-Audio fast track pro which is a USB interface.
You can't. It needs a computer.
The best way you can use Guitar Rig 4 in Pro Tools 8 is by making sure you have the M-Audio Fast Track driver downloaded.
File> New Track Then select the type of audio file you are going to record, if it is a single mic or direct in select mono.
You can use whatever method you want to record a video of yourself. Import the video in to the computer. You can then add a video track to Pro Tools and then import the video in to the project.
Neither is as good as the full version, but from those two - Pro Tools MP9
Select the section and press delete
The proper way to track music in Pro Tools LE 7.4 so that your loops from your keyboard line up in grid mode is to open grid mode and use the hand selection tool to line it up.
There is no Pro Tools LE 9.
You need a microphone and an interface, and creativity. Make new audio track, press record and start playing.