Nice lens and a decent camera. Here's a link to the
details about the MG, although you may still be benighted by technical information. Try downloading and printing a copy of the manual from
Pentax-Manuals.com - its free and a very high quality scan. The password is "Pentax"
The learning curve is no worse than learning the Aperture Priority function of a DSLR. Av is the only function on the MG - there is no manual mode. That should make the learning process fairly easy.
Although you may not want to spend the money, may I suggest you consider having the camera inspected and brought to original spec.'s by this Forum's favorite Pentax technician,
Eric Hendrickson? The link sends you to his website, where he describes his business and service - quite excellent and inexpensive for what he does, and no risk to you! Read the estimating information in the right frame.