I didn't find info on all of your questions, but you can look around these sites.
These links will help:
I was not able to find a clear discussion of why steer away from white vinegar and toward raw apple cider vinegar...but in a lot of the information, white vinegar is used a cleanser and as a cheap form of vinegar. ...raw apple cider vinegar is probioitc...so it does more than just 'cleaning' it also rejuvinates.
...if you are taking this for acid reflux on a regular basis...then this tells you something else is the issue and should be dealt with more directly versus symptoms...also with using it for dandruff, ect (which I have). that is, this can be used to address symptoms and deal with issues on a certain level, and so valuable to keep around. but if this is being used on a regular basis...then a better look under the 'hood' may be in order and address the issues at a more systemic level.
also, in general, having some rotating fermented foods seems to be an adaptive approach (and in some ways a paleo perspective)...just rotate them. ...sauerkraut has cabbage and can be estrogenic, miso - the same, etc. ...but also good to rotate because there are different biotic strands...and roughly 80% of immune system is in gut (also where most of seretonin is made...but us moderns tend to have too much seretonin or are resistent...read Lights Out)...and there is more neurons in our gut than head...so 'the first or second brain' thing.
hope this helps