Is my kimchi still okay?

IF you've made it with the correct amount of salt, it is likely fine. Kimchi (all lacto-ferments) will continue to ferment. It may get too funky for your liking, but it will not be a hospitable environment for anything that will make you sick. It will not "go bad", in the sense that it could make you sick. If it was under salted, all bets are off. If it gets slimy or is growing fuzzy mold, you probably want to discard.

Kimchi will continue to ferment and get sour over time. This is perfectly normal, provided you made the kimchi correctly. If it gets too sour for your taste, it's time to use it in other foods:

• Wash it and use it as a wrap (ssam)
• Use it in stew (kimchi jjigae and budae jjigae)
• Use it in dumplings, Korean pancakes (buchimgae) or fried rice (bokkeumbap)

In fact, people will sometimes store the kimchi at room temperature to quicken the souring process, so that they can use it to make these other dishes.

My kimchi (still in the fermenting crock) tastes very vinegary. Is it still good to jar & refrigerate?

Yes. This is perfectly fine. Thanks to lactobacillius, kimchi ferments even after you put it in the fridge, but at a much slower rate. The extra strong, vinegary taste that you mentioned is most likely a sign of mild over-fermentation, which isn't a bad thing at all; it just means that the kimchi will smell and taste stronger, and might have a stronger effect on your stomach.