when is the optimal time to cut my bittersweet?
If you want to cut the decorative branches, you can do so whenever it has produced berries. If you want to prune it back, you should do so in late winter or early spring. Here's an article for you:
https://www.gardeningknowhow.com/ornamental/vines/bittersweet/growing-bittersweet-vines.htm
How to tell by branches if i have a male and female branch
This will be impossible. You will need to look at the sex organs of the flowers, unless you have access to a lab that does this kind of work.
https://www.gardeningknowhow.com/ornamental/vines/bittersweet/growing-bittersweet-vines.htm
my plant is 6yrs old and has full sun all day the vines are huge but no orange berries. Can I cut it back and see if it comes back stronger?
You need a female plant, since males will not produce berries, but you will need a male around to pollinate. It takes two to tango, so to speak.
This article will help you with the care of the plant:
https://www.gardeningknowhow.com/ornamental/vines/bittersweet/growing-bittersweet-vines.htm
I have heard to cut and dip them to kill them then pit in large black plastic garbage bags. What next?
There will be no need to dip the cut parts into herbicide. Putting them in a plastic bag will do the trick without poisons. What you DO put herbicides on will be the stump left behind. This will prevent it from growing back. You will, likely, need to keep applying this to all new instances that come up over the next couple of seasons, though.