solving problems and crimes..can you solve the following cases?

1) what letter belongs to in the empty box?
O T T
F F S
S E

2) write a sentence to describe this pattern..
3,8,13,18,23,28,30,31,32

please help i don't understand.

1) E

2) The first six numbers are separated by five; then there is a gap of two, and the last three are separated by 1.