Re 1:
Your description suggests some data are available from your practice management software, and other data are somewhere else. If so, the best approach might be to export the data from the practice management software to a CSV file that you can then load into, say Excel and combine it there with your other data before doing the merge.

A word mailmerge can't use a PDF as a data source and, although automating Adobe Acrobat (you need the Pro version) isn't all that difficult, extract precisely the data you want could be a challenge.

Re 2:
I have no knowledge of the Excel system to which you refer, so I can't advise on that front.

Re 3:
It's all self-taught. I'm something of a pioneer in the field (no pun intended).

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]