Woman covering the feet in salaah

Q: Is not covering the feet below the ankles for woman against sunnah? I have severe waswasa and I found out that except for Hanafi's, others consider the feet as awrah. Are my prayers invalid as I didn't cover it after knowing about the ruling. Why do Hanafi's not consider the feet as awrah. I feel scared that my namaz isn't valid. What should I do?

Filling the gap in the saff if the muqtadi leaves during salaah

Q: There is a rule in Bahishti Zewar that it is makrooh to stand alone in a row. The person should pull a person back from the row before him. What happens to the gap formed by the exiting of the said muqtadi to fill the previous row?

If a Muqtadis wudhu breaks during prayer, should he just leave and leave a gap in the saff? What should he do in this regard?

Child born out of wedlock

Q: If a child is born out of wedlock (through zina), will he be attributed to the mother or the biological father? The biological father is pleased to take him as his own child and give him his surname. Is he the responsibility of the biological father and will the biological father have any rights over him? What is the shar'ee ruling in regard to a child born out of wedlock?