Leak from brake reservoir

First check the sides of the reservoir to see if it's wet. If it is, suspect the cover is loose or the bladder seal is torn, deformed, or not seated in the groove in the cap. If it's not wet and the only fluid is down on the bottom, it's possible the reservoir is pulled up so the tubes aren't seated in the rubber gaskets. Those gaskets could be cut too. They aren't available separately. You'll either need a rebuilt master cylinder or visit a salvage yard and rob them from an old master cylinder.

Yup. It's just held in by magic. Well, that and the friction fit from the rubber inserts. The tubes at the bottom of the reservoir are formed with a sort of a flare at the end so they won't pull out very easily. In fact, if you have to transfer the reservoir to a rebuilt master cylinder, it's real helpful to use brake assembly fluid, if you can still find it anywhere. That is real thick brake fluid but it's slipperier than regular brake fluid.

I should mention too, just to be safe, ... Never ever get any type of petroleum product mixed in with brake fluid so don't use silicone spray lube or any kind of oil to make sliding the parts in easier. Nothing but brake fluid contacting brake parts.

That reservoir is a very low-failure item, and I'd be real surprised if you cracked it. That plastic tends to bend instead of crack. It's more likely the rubber insert got torn. You might consider looking for a salvage yard where you pay your buck, throw your tool box in one of their wheel barrows, then head out and practice removing the reservoir on one of their cars. If you can pull out the rubber parts, so much the better. If you live anywhere between Indianapolis, Ohio, down to southern Georgia / Alabama, there is a real nice chain of yards called Pull-A-Part. They are very clean and well-organized and parts are very inexpensive. You can do an internet search for them too. I was also to a similar type of yard in St. Louis, but it was very messy and expensive.