One of my colleagues (want, wants) to start her own business.

여기서 wants 인것은 내직장동류중 한명이라서 단수이기에 wants가도는건가요?

The agreement to merge the two companies (was, were) settled on Tuesday.
여기서에서 주어는 agreenment인가요??

The sidewalk in front of the houses (is, are) cracked.

여기서 sidewalk가 주어라 단수라 is가되는건가요?

There are several interviewees, but Jane is more qualified than (one, another, the others).

여기서 인터뷰하는사람들이 3명이상기기에 another가안되고  the other가되는건가요?

Most of the employees are diligent, but a few of (they, their, them) are lazy.

but부터가 목적어 이기에 목적격인 them이들어가는지요?

설명은 없고 독해만있어서 햇갈리네요