Salaah

Forgetting to recite sunnah qiraat in salaah

Q:

1. Before starting witr, I made an intention in my mind that I will recite the surahs which are sunnah to recite in witr. Then I said softly that I make niyyah to pray 3 rakat witr, but I did not say anything about which surah I will recite. During the prayer, I forgot to recite the sunnah surahs in the first two rakahs. Then I thought that I will do sajdah sahw, but I forgot to do that too. Is my witr valid?

2. Is sajdah sahw waajib if someone intends to recite a specific surah and then forgets to recite it?

Imaam making masah on socks

Q: The place where I live is a very cold place so the imam of the mosque always wears normal socks and does masah on the socks. Is it better to pray behind him without doubting or pray behind him and repeat the namaz make jamaat at home with one's family members? Which option do you recommend?