Salaah

Looking at the next Musallee to determine how many rakaats one missed

Q: A person arrives late to the masjid and misses a number of rakats with the imam. When the imam says salam, he thus has a number of extra rakaat to make up. But he doesn't remember how many. In order to find out, may he pray slowly and see how many extra rakaats the people around him do, since they joined the prayer at the same time as him?

Performing Salaah at home when there is a severe downpour

Q: In the UK the weather is often cold and wet and I am a young teenager. Sometimes I want to go to pray salah with the jamaat but due to the weather my mother stops me fearing that I will become ill. Shall I disobey her and fulfil Allah Ta'ala's command or obey her and read at home? Would I get a sin for not obeying my mother or missing salah with jamat?