Factors that break and don't break the fast

Swallowing while fasting

Q:

1. I regurgitated and I tried coughing it out but even though it felt like a lot of regurgiation, it was difficult to expel, so only some of it came past my throat. Due to the difficulty, I swallowed. Is my fast valid?

2. Also, there are times where I regurgiate and feel the contents at the top of my throat or past it, however i’m not completely sure if it can be expelled or not and i’m afraid if I cough to test if it will come out, i’ll end up essentially forcing it to come out and vomiting. So I usually just swallow it. Is this fine? I regurgiate quite frequently so this brings me trouble.

Scarf coming in one's mouth while fasting

Q: Frequently, when going in sajdah, the fabric of my headscarf or the prayer mat ends up on my lips or in my mouth. This is an issue when I’m fasting. I don’t know if anything like microfibers or small hairs have entered my mouth. Today this happened during salah but I couldn’t feel anything in my mouth after it occurred so I assumed I could swallow as usual.

1. Was this correct?

2. If this happens during salah, and I feel something in my mouth after, do I have to spit?

3. If this happens in salah or near the end of it, do I have to check in a mirror afterwards to see if anything inside my mouth?

Swallowing the moisture on one's lips after wudhu while fasting

Q: The moisture left on my lips from washing my face/mouth during wudu, is this safe to be licked and ingested when fasting? Usually after I wiped my lips in wudu, I have to spit and then let my lips air dry and/or wipe with a tissue until dry. Today after wudu, the majority of my lips were dry but in the corner of my lips I felt a coolness, which may indicate that there is still moisture from wudu left. I licked that area. So now I’m just wondering if my fast is valid.