Why does the vine of a squash plant turn black?
I would inspect your plant thoroughly for signs of squash bugs. Squash bugs would cause the vine to blacken. For more information on squash vines, please visit the following link:
https://www.gardeningknowhow.com/plant-problems/pests/insects/squash-bug-control.htm
Do I snap or pinch the squash off? Or should I cut? If I cut, how much of stem do I cut off? Also, if I cut, will a new one grow? Thank you.
Here is an article about harvesting squash: https://www.gardeningknowhow.com/edible/vegetables/squash/when-to-harvest-squash-best-time-to-pick-winter-or-summer-squash.htm
Once ripe, the squash should be easily pulled from the vine. However, many people prefer to cut them from the vine, leaving about an inch or two of stem.
Squash plants dropping blooms, no squash. A deficiency?
This is typical behavior for a squash plant. They will produce mostly male (non-fruiting) blossoms early in the season and will gradually start to produce more female blossoms as the season progresses. The male blossoms typically drop from the plant and seemingly disappear. Give it some time and you will see it start fruiting. Here is more information: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossoms-falling-off-vine.htm
Over the weekend, a friend came over to look at my garden. One of my squash plants had a few of its leaves beaten up by hail. While I wasn't looking, my friend cut the beaten up leaves off the plant. Now it is drooping and doesn't have the life in it that it did. Is there anything I can do to help it become healthy again?
While it's okay to prune some, you should only try to remove the growing tips so as not to leave large wounds that may draw squash pests and diseases. It's possible that the plant is now under stress and given some time it will hopefully recover on its own. I would treat the plant with neem oil, a safe and effective pesticide and fungicide. This should help in the event that any pests or fungal issues arise. Other than that, you should just keep it watered. This article has more information about neem oil: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm
My squash did fine the first five weeks of harvest, after that 70% of my squash is rotten on the vine. What am I doing wrong?
Are the squash just rotting on the ends? If so, this would be attributed to blossom end rot and this article can help with that: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
If the entire vine and squash are rotting, this may be an issue with vine borers. This article will help:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-pests-identifying-and-preventing-squash-vine-borer.htm
How do you know if the squash is pollinated? Will the fruit become longer or should I assume that it isn't and pollinate it myself? I do have a decent amount of bees around, so I have assumed that they are pollinated since the flowers go limp. Am I correct?
If you have vegetables growing the plants are being pollinated. The bees are doing there job!
Here is a couple of links with more information.
https://www.gardeningknowhow.com/edible/vegetables/squash/pollinate-squash-by-hand.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/tips-for-growing-squash.htm
Why are some of my squash getting about three inches long and then turn yellow and dry up? Also, my small tomatoes are turning black on the ends.
With the squash, it sounds like a pollination problem. These articles will help: https://www.gardeningknowhow.com/ornamental/trees/teak/insect-pollination-process.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-fruit-falling-off-the-plant.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/pollinate-squash-by-hand.htm
The tomato has blossom end rot. Here is more information: https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm