[[My questions is, what documents am I required to submit with my 1040 &
schedules?]]

Carefully read the instructions and you'll find out what you are required to attach. All of the rest of it you simply keep for your records, and do not attach to the tax return.

[[ Obviously my W-2's. ]]

Obviously..

[[Do I also send in copies of all of my
1099-DIV's? What about the mortgage interest.]]

Nope to both...

[[ Do I send in the form the bank
sent me showing how much I piad? Do I also send copies of the notices from
church & United Way, showing how much I've given this year.]]

Nope to both again...

[[ Or, are some of
those things that I just need to hold onto, in case I"m audited?]]

Basically correct. Again, read the instructions carefully. You'll find that, generally, other than W-2 forms and 1099R forms with federal withholding, nothing else (with respect to forms) is required to be attached to the tax return.

TMF Taxes
Roy