For the doseage levels on the vitamins…I would do 100-200% daily value. Selenium absorbs best if taken with vitamin E at the same time.
As far as testing for SIBO, h.pylori, parasites…a doctor’s office would have to do this. These each have symptoms similar to candida. Most people who have candida have parasites and some of us may have other bacteria or flora overgrowth.
I personally think you are limiting yourself by not consuming animal products. SF722, cod liver oil, and protein/minerals from meat are all things that can improve your situation. I understand its a personal preference/belief but you have health problems as well.
If you want an alternative HCL product I would check out zypan by standard process.
The bitters could improve your digestion by getting you to produce more enzymes and thus you break down and digest your food better. I personally tried digestive enzymes and these work in a similar manner, it just does the work instead of your body doing the work.
I would take a cap full of ACV or spoonful at a time. Make sure its raw organic ACV. Maybe mix with water.