1. which tense do we use for habitual actions ? 2. which tense do we use for actions in progress ? 3. which time expressions do we use wits each tense ?

1. Used to, Для привычек, иногда используют "Would".
пример:
When I was young, I used to play toys.
When I was young, I would play toys.
2.Continuous Tense
Пример:
Sally is doing her homework at the moment
3.
    1.last;ago;Than I was...
    2.At the moment;These days;Now;Nowadays.