I think you are safe on the bowel movement part. Seems like you are eating more, hence the extra bowel movements. People have different movements believe it or not. I go frequently a day. My surprise when my friend told me he goes about 3 times a week!!!!
LOL. About the residue... just wipe wipe wipe. Maybe invest in some 'Wet Ones' that are moist napkins.
Now your teeth. Are you in the US? There is a payment option called carecredit. It is like credit card for you anything medical. You should invest in one. You are 22. It's time you take responsibility for the things that affect you. A lot of dental office also have payment plans. I suggest you go in for a consultation and work out a payment schedule to get this worked out. Bad dental hygiene can effect different parts of your health so I would not lose sleep over this! Get the consultation so you know EXACLTY what you are dealing with. You may not need to get all your teeth pulled and their may be other alternative.