He’ll be fine. Mine had one sad, dry branch and now he’s a jungle princess. These things are very robust and can regenerate from big neglect.

Salvageable! Check the soil, it might need to be repotted, especially if the soil is dry and/or compacted. Other than that, water roughly once a week and keep it in a sunny window.

You can also take a cutting and put it in a glass of water as backup. Make sure to get at least one node (the wider area in the stem, usually with a little nub of aerial root starting). Cuttings with leaves attached will have an easier time.

Absolutely not, it’s just a bit leggy. You can either cut the individual pieces and replant them in dirt and they should sprout roots after a while, or you may be able to put them in water for a while (this method takes longer). As long as there isn’t any rot anywhere