To answer the nail polish question...
If your nails are pretty bad, we would suggest you try NOT to use nail polish at all for at least the first couple of weeks (or longer if possible). The FlexiNail won’t get past the polish coat – so it can’t be absorbed into the nail. Without polish, this gives your whole nail a chance to absorb FlexiNail. After you start to get your nails back on track (assuming they are really bad to start) then use polish as you want (sparingly with breaks if possible). If you are using FlexiNail just to improve your nails - then we still suggest at least several days, a week or even longer at the start without polish - then just try to minimize the harsh on-going use of polish remover etc. Remember, if you are using polish, make sure that you are getting FlexiNail under the cuticle into the matrix area and also up the sides of the nail and into the skin all around the nail.
If you keep the nail matrix (that's the part under the cuticle) conditioned then this new nail that grows will be in better shape from the start - a lot more efficient that trying to change the nail that's already there. Your results with FlexiNail won't be as dramatic or fast when used with polish - but get the conditioner to the matrix area and you will still see benefits when this new nail growth grows out to the end of your fingers.