Who are you expecting now? vs Whom are you expecting now?

[Hanifasmm]

Hi everybody,
1.Who is this for?
1a. For whom is this?
2.Who are you expecting now?
2a.Whom are you expecting now?
3.Say whom you think will get the prize?
3a.Say who you think will get the prize?
4.Who do you think we met?
4a.Whom do you think we met?
All the pair of sentence are correct grammatically?
Does each pair mean the same?
If you find mistakes, please guide me.
Thanks.
Er.S.M.M.Hanifa

[Mister Micawber]

1.Who is this for?-- OK
1a. For whom is this?-- Very, very formal
2.Who are you expecting now?-- OK
2a.Whom are you expecting now?-- OK, formal
3. Tell us whom you think will get the prize.-- Wrong
3a. Tell us who you think will get the prize.-- Right. The pronoun is the subject of the verb 'will'; 'you think' is a comment clause.
4.Who do you think we met?-- OK
4a.Whom do you think we met? -- OK, formal.
_________________
Native English teacher at Mister Micawber's