The flame is adjustable, though it burns rather intensely. In other words, it is difficult to obtain a simmering level.
Everything is the same except that the Java kit includes the coffee press, etc. As far as contents goes, it doesn't really rattle any more than the original model.
The PCS stove is designed to utilize the 1.0 Liter Aluminum Companion Cup only. Sumo cups have a larger diameter, and although the Titanium versions might fit, though I would not recommend it.
Yes. This will help the water to boil faster. You do not need to worry about the lid melting. This will not happen - it's made with a heat resistant rubbery plastic.
They are both the same stove unit. The only differences are that the Java kit is only available in Green, it come with a Coffee Press and a sample of Coffee Beans.