Repotting plant as it was looking poor at stem level and it was potted in vessel with no drainage holes. Was moldy in old pot. Concerned about brown discoloration running up stem. How do I correct this issue?
Your plant doesn't look too bad at all. If its roots have been sitting in wet soil without good drainage, repotting it should help a lot sing well-draining soil. You may also need to trim away any roots that might have rotted. Here's an article for you:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/advice-for-christmas-cactus-care.htm
One of the plants the leaves are changing to a reddish color and is wilted. The other is wilting and leaves are dying. The soil is super dense and super wet. They are currently blooming, what can I do to save them?
Ensure that they dry out a couple of inches down into the container, and make sure that they are in a light aerated cactus mix with some compost. This will stop root suffocation.
I received a Thanksgiving cactus plant on Dec. 23, 2021. It arrived with it's buds tightly closed. Then within a week or 2 it bloomed with a moderate amount of pinkish red blooms. Now all of the greens are shiny and full but there are hardly any blooms left and the few that are there are withered and look like they will be dropping off of the plant. Is 2 weeks of blooming all I will get or will this plant show it's pretty colors for a lot longer? When do I fertilize and when do I cover it over with a box to make it think it's dark for more hours than it is?
There are a few things that you need to know when caring for these plants. They can be a bit particular. Here are some articles that will help you to know what to do with them, next:
These are very easy to propagate! The process will be the same among all of the related species:
What time of the year?
You can prune anytime after it blooms through spring. This article should help: