LOOKING与LOOKED的疑问

LOOKING与LOOKED的疑问
A：Tommy hated school and always looking for excuses not to go.
B：He spent more time at home than he did at school.
Q1：A句中为什么always 后面会是looking而不是looked呢?如果将looking 改为looked可以么?句子的意思会改变么?会有啥变化呢?
Q2：B句中为什么会有个did 出现呢?它能起到怎么样的作用呢?
副词后面的动词一定要是ING形式的么？