Hello there!
You pose a lot of good questions, many of which could be considered subjective to different individuals. If you plan to actually take "pharmahuasca" then the extracted forms of MAOI and DMT are necessary. I myself prefer pharma over Ayahuasca mainly because it is easier to ingest. Another member (Jees) and I had discussed
pre-dosing some harmalas before ingesting your full dose of MAOI and then DMT. Ever since that discussion it has been my favorite way to take pharmahuasca. You can read about my trip report using this method
here if you are interested.
As for becoming familiar with the MAOI and fasting, I say yes to both. It is good to see how the MAOI will affect you before jumping in headfirst to the experience and fasting will ensure a better trip all around. There should be less discomfort in the digestive tract if there is nothing in there to disturb the medicine, IMO.
As for taking them together or at the same time, that is still up in the air for most people...your best bet is to try both ways and see what works the best for you. With the pre-dosing method I took my first dose of MAOI, then waited about an hour or so, took the other "full" MAOI dose, waited about 15 minutes and then took the DMT. Of course, that is just me. All experiences, including yours, can vary significantly depending on many factors.
Set and setting are the most important things to consider before making this plunge. I typically go into it with no music, which is weird for me because I am a musician but sometimes I find it a bit distracting with any form of DMT (I did have a few good vaped experiences with some classical music but that is a different story altogether). I recommend low lights or candles and to be somewhere very comfortable where you can lay down and stretch out. Lots of blankets and pillows for comfort.
I prefer to extract my harmalas from sryian rue. It is cheap and plentiful, not to mention the extraction process for it is incredibly simple, although a bit time consuming.
I can't say much about diet though. I usually just eat a very light meal at least 6-8 hours before journeying. Or sometimes I fast the whole day and throughout the experience and will eat on the come down or after baseline has been reached. I would stay away from fatty foods if possible to minimize discomfort.
Anyway, these are just some ideas. The best way to find out what works for you is to jump in and test the different waters. Good luck with whatever you decide to do!
PEACE