Hello,
DMT does not create any tolerance, in whichever form you take, at least in physical terms. So you could take an oral dosage in the morning, then again at night, and you definitely wont feel less later at night (maybe even more, considering some alkaloids might still be lingering around). With vaporizing also, you could keep launching over and over.
With that being said, while there is no physical tolerance, quite a few people who use DMT repeatedly over a certain regular period of time feel that after a while they dont get something good/positive/constructive/beautiful out of it anymore. It's as if hyperspace has a natural regulatory process that tells people when it's time to take a break. Take a look at this FAQ entry:
FAQ - DMT Frequently Asked Questions and Troubleshooting Guide - DMT-Nexus Wiki
Just listen to yourself regarding frequency of use, try to be reasonable, knowing that 'how much is too much' will depend on several contextual factors that nobody can really say for you. Just make sure your "normal" life isnt being forgotten, that you are trying to be healthy, are still fulfilling your responsibilities and are present and helpful for those around you
As for dosages, your dosages seem, at first sight, more or less ok. A properly vaporized DMT dosage is around 20-30mg IME, but this is hard, if not impossible, to succeed with the sandwhich method. With that method, 50mg is more likely the dosage you'll need. Use as little herbs as possible, and go easy on the lighter, inhale slowly and hold the smoke as long as possible. Go for second/third/fourth hit if possible (if you are looking for a breakthrough).
I wouldnt wait sooo long between the harmala and the dmt. Maybe taking half around 30-40mins before dmt and the other half together with the dmt could be good... But then again there seems to be no consensus whether to take dmt and harmalas together or harmalas before, or some harmalas before and some together. 3g peganum harmala is ok dosage. Are you going to make a tea? Maybe research into extracting it in the future, its easier on the body IME.
100mg oral dmt is a good dosage for some people, too much for some people, and too little for others. Maybe start rather with max 75mg for th first time, until you know your own metabolism ? You can always vap some dmt on top of the oral dosage if you dont get where you want (as was your plan it seems).
I dont think that will wear off in 1 hour only, maybe more like 2-5 depending on your personal metabolism. If you still feel like vapping some 25mg dmt, I dont see why not, just dont force yourself if you dont feel its right
Good luck, let us know how it goes.