1) I did remove the buildup when it became too much but, during the stages leading to the dormancy of my EC I didn't have any buildup of skin to deal with at all.
2) I moisturized my lips every chance I could get either with Bepanthen or coconut oil. I still use coconut oil to this day.
3) No, I no longer use Bepanthen.
4) Yes, the inside of my lips (mucosa) were very compromised. Yes, they would go white and there was even a type of white inner lining underneath that I could actually see. I no longer have that condition anymore though.
I dealt with it by using oral hygiene products that neither have fluoride nor SLS (sodium laurel sulfate) as ingredients. I also brushed my tongue after brushing my teeth & I used a mouthwash that was alcohol-free and also had xylitol in it. The best mouthwash I have found is Biotene (pictured below) and I still use it to this day.