All I have left in my hand are Miscellaneous Action Cards. Can I play 2 of them towards a Situation?

Yes. If you want to get rid of these cards, you may play 2 of them. The result will still be a “0” contribution towards the Situation. Note that you will also only be able to draw one replacement.

If I am a revealed neighbor, and my teammate(s) are also revealed, can we talk at the table and say what we are going to play towards Situations?

This is a matter of intelligence. Sure. You can say what you’re playing. But you’re also letting others know what you’re playing who may change their cards based on your chatter.