Salaah

Reciting in sequence in Salaah

Q:

1. When reading surahs in our Salaah is there a specific sequence to choose a surah to read? e.g. Do we have to start from Wadduha then followed by the next surah?

2. Is it ok to read a short Surah followed by a longer one? e.g. Wal Asr and then Izaajaa'a. Please explain what is the correct way?