Some prayer and dua questions from a new Muslim (Sunni)

Assalamu alaikum! I’ve got a bunch of questions floating in my head and I keep finding mixed answers, so I thought I’d just ask here all at once. 1. In sujood, should my eyes stay open or is it better to close them fully? 2. My knees really hurt when I go down for sujood or sit in that upright position after it (I think it’s called julus). Can I pray sitting down? 3. Is it okay to pray while wearing a t-shirt? 4. Let’s say during prayer my t-shirt rides up or my pants slip down because they’re tight, and some skin shows that shouldn’t be seen (awrah stuff). Can I just tie a sweater or jacket around my waist to keep things covered? 5. In tashahhud and salawat, am I supposed to move my finger or keep it still? 6. When’s the right time to make dua-during the prayer, after it? If it’s during, which part exactly, and do I say it out loud or quietly? 7. Can I just make a random dua anytime during the day when I’m not praying? And do I need to say it aloud or can it be in my head? 8. How exactly should I sit in julus? Like, how do I place my feet and legs? Pictures would be super helpful if anyone has some. 9. When making dua, I cup my hands together. Once I’m finished, what do I do? I’ve seen people wipe their hands over their face, almost like washing it with water. Is that only over the mouth, or is the whole face thing just made up and I can just drop my hands? Sorry for throwing so many questions at once-it’s just been on my chest. InshaAllah someone can help, and even if you only know a few, please drop the number with your answer. Jazakum Allahu khairan! 😁