If it have to be in Usted, it would be:
1. Déjeme comer en clase
2.Déjeme dormir en clase
3.Deme más tiempo para hacer el examen
4.Déjenos salir de la clase pronto.
5.Escriba ...whatever...
The second option "ensalada, pizza, feminine" would be correct. You eat both salad and pizza, and in Spanish these are both feminine nouns.
~I hope this helps!~
