Doubts About Purity and Fasting Validity

Salaam, If there was pee and then I sprayed it with water so that it was wet and then it dried but I didn’t pour an overhwnlmign amount and then later after a couple of months I used a tissue to scrub the area slightly and there was no change in colour (as in no yellow stain) - is the pee removed in Islam? I keep overthinking the time my toddler cousin peed on the stairs and if it’s been washed properly as we didn’t overwhelm it with water - my wet trousers touched that area and now I’m wondering if impurity transferred to my bed and if my prayer was valid, did anything transfer to my trousers if there wasn’t a smell and I couldn’t see a difference on them? Also, I rinsed my mouth in wudu and had leftover moisture - I can’t confidently say that I had some water in my mouth but my mouth felt really wet. I swallowed because I didn’t want to spit too much as it would fuel my waswas and I had a feeling that if I spit it would leave a trail of saliva and I’ll be continuously spitting because there would be saliva again in my mouth - this is all speculation and what I assumed would happen. I also remember seeing somewhere that it’s okay to swallow and I swallowed and now I’m wondering if I’ve broken my fasts. There wasn’t a noticeable pool of water but my mouth was very wet, I swallowed knowing this - is my fast valid and do I need to pay kaffarah? If you can only answer one can you answer the first one.