Larry,
Yes, you can plug your guitar into the mic/line input jack and play along with your midi file backing tracks--piece of cake, lots of control and it really will sound great.
You cannot record the guitar sounds into the keyboard because it's going through the mic/line input, which is an annalog signal. However, you can connect the keyboard to your computer and record everything that comes out of the keyboard as a WAV file using the instructions I posted at
PSR Tutorial.com and get excellent results.
Good Luck,
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)