Thank You Etiquette

I know this is probably a stupid question but....

FH and I over the past few weeks have been getting alot of wedding gifts sent to us, some in the form of a check, but mostly gifts from our registry. I know some of these gifts were from friends who couldn't make it to my shower two weeks ago and I've gotten the majority of those thank you's out already.

My question is do I send a thank for:

A guest that sent us a gift already and has responded they WILL be at the wedding.

and

A guest that has responded they are not coming to the wedding and have sent us a gift.

Or do I wait until after the wedding to send those thank yous.

And as far as the monetary gifts, is it okay to deposit those checks before sending a thank you?

It's all very confusing to me!

TIA

I sent thank-yous as the gifts came. If they are coming to the wedding, I will send them another reiterating our appreciation and thanking them for coming.
I got one wedding gift 3 months before the wedding and I just figured it would be rude until after the wedding to send a thank-you.

We've been sending thank you cards out as gifts have come in.. it helps get them out of the way and less to do after the wedding!
I would cash the check also - you don't want to screw up someone's bank balance by leaving it for a few months.