Problems with tense and which word to use?

Could you please tell me how to properly say the following sentences?

1 What I saw is (what's) on the tape.
2 The rings are the last things we are buying/will buy?
3 Other than those 2/Apart from those 2, no one else hates each other.
4 She's changed from when I last saw her/since I last saw her.
5 The person who/whom you mention is here.
6 Every time/Whenever he looked at me, he was smiling/he smiled.

Thank you