the use of "the rest"

I wonder if "the rest" is singular or plural:
1. Three of us will go, the rest is/are to stay here.
2. The rest need/needs no telling.
3. Tom is going to the zoo, the rest of the students is/are going to the park.

Actually, it depends on what the speaker or writer means: if 'the rest' is treated as a unity (i.e. a group), then it's singular; if treated as several people, then it's plural.

So: they both work, depending on what you mean.

Same for other collective nouns: The Beatles was/were a great grounp, the States is/are the dream of many people, etc.