Used To

Question 1

I used to verb

Answer 1

It’s the same as gerund but context is needed to decipher each.
Ex: I used to eat rice.
ごはんを食べて(い)た
Ex: I was eating rice.
ごはんを食べて(い)た。

Question 2

Used to___

Answer 2

Godan: て form + いた
読んでいた
Itchidan: ていた
食べていた

Question 3

A long time ago I used to ___
Before I used to ___

Answer 3

(むかし)昔、noun + verb
(まえ)前、Noun + verb

Question 4

I didn’t used to____

Answer 4

Stem + ていなかった
Ex: 食べていなかった
Add 昔、前 to be more specific