I'll try to explain my question...If you plant a yellow marigold and an orange marigold...are the seeds from the yellow one yellow?

Usually. I've not seen otherwise.

If you plant Nicotiana mix...will the pink be pink? and so on? I do realize that a hybrid is not guaranteed the same as the original...

Most ornamental nicotianas are self-pollinating. Pink should beget pink.

Is this different for annuals to perennials?

No.

If it's a complicated answer...please feel free to direct me to researching in the proper area. Thanks so much!!

This is the seed saving forum...you're in the right place ;-)