I have carefully extracted 100 g of Root Bark. I am pretty sure there are no alks left because 2 last extractions (out of 7) yielded nothing. Alltogether I have collected 5 g of TA. No acetone cleaning was performed.

I have a couple of questions.

1. Is this yield normal?

2. How would you recommend to calculate a good flood dose of TA?

3. Suppose a test dose (approx. 1/3rd of the planned flood dose) was taken today. Will there be some tolerance if this person decides to take the flood dose tomorrow?

I'm pretty sure there's no tolerance build up. Whatever you take now will be added onto later when you dose again. You'll go deeper.

I'm 125lb and the sweet spot for TA for me is 1.5g-2g TA

Dunno about the yield.

Yield wise, that sounds about right, I've heard that iboga root bark varies from around 1-6% alkaloids by weight. And with my extractions, the first extraction/vinegar soak seemed to pull the vast bulk of the alkaloids.

I would recommend maybe testing a 1/4 or 1/5th of your flood dose and saving the rest for your flood experience. Will be fine having this iboga in your system, closer to how the Bwiti use it over a number of days, but I would still save the bulk of your yield for the flood session, but a test dose prior to check sensitivity is a great idea.

Regarding dosage advice, this is worth a read:

http://eboka.info/eboka-talk/iboga-protocol/