What's your question? Ask

Try hosing or plucking the worms off. Remove as many of the lower leaves as possible from the plants, as this is where they lay their eggs, which are dark green.

To prevent worms from burrowing into the heads, try placing the entire head in pantyhose or other suitable nylon stocking until ready for harvesting. This is often done when the worms/butterflies are most prevalent, in spring and summer.

The use of Bacillius thuringiensis (Bt), a non-toxic, biological insecticide, is effective and is specifically targeted towards worms/caterpillars. It’s also safe and can be used on most garden vegetables. Using Bt will not harm any beneficial insects, including natural enemies of these worms. Another alternative is neem oil.

This is typically caused by a watering issue. It can be caused by too much or too little water. Likely, in this weather, it is too little. Try increasing water to the plants to help reduce the browning.

I don't personally, but I have heard from "old timers" that doing so for 10 minutes or so will encourage any stowaway bugs to vacate the cabbages. I don't know if that is true or not though.

You need about three or four weeks of below freezing weather.This should soften them up.

They are bolting. This means that the heads will not form. Unfortunately, there is not much you can do but pull them out and start again. This article will explain more about bolting:
https://www.gardeningknowhow.com/edible/vegetables/vgen/what-is-bolting-what-it-means-when-a-plant-bolts.htm

Yes, all parts of cabbage are edible.