1) Depends on what is in the gel pill. Most of them are oil based and those are just expensive poop. But some gels, like my liquid ibuprofen is a gel and we absorb those easily enough so the answer is, it depends. For VITAMINS, stick with dry forms.
2) The ONLY study as to what we absorb was done for fat and it was a very small sample size of people. That study suggested 20% of fats absorbed. Common THEORY is that we absorb about 60% of the protein we ingest and anywhere from 60-100% of the carbs. And the sugar based carbs are figured at 100%. But there is no study.
These threads give you some idea of how it all works:
http://bariatricfacts.org/threads/ds-math.735/
http://bariatricfacts.org/threads/fats-are-not-the-enemy.3185/
BUT it is theory NOT FACT!!! Each person has to find WHAT works for them and things will change as you get further out.
3) I started probiotics about 3 months after surgery after I was getting my vitamins in. As to whether we need them or not, the jury is out but gut health (and that means good bugs) need to be in abundance to avoid bloat/gas/stinky farts/ etc. If you don't want to take a probiotic, at least eat foods rich in good bugs such as yogurt, kefir, etc.
http://bariatricfacts.org/threads/get-larger-variety-of-probiotics-through-food-sources.665/
4) Calcium is non negotiable. How much is needed is based on your labs, and that includes your vitamin D level AND PTH.
http://bariatricfacts.org/threads/parathyroid-check-your-d-calcium-and-pth-first.1065/ Some handle pills, some prefer chews, but it HAS to be calcium citrate. Repeat, CALCIUM CITRATE! If it does not say citrate ON the front, it is the wrong kind.
5) My surgeon had to order my labs WHILE I lived in the same city as he did, my PCP was hogtied by the system. Now that I am in another state, my PCP orders mine. If your PCP doesn't cooperate, maybe it's time to find a new, fresh out of school, PCP who is willing to learn.