A: If you can find a way to hold water in tube form. Likely no. The Coleman camp burner and pot really works amazing when camping
A: You are limited only to the size of the tube tray. Chicken and fish are ideal for the sun oven I am not sure about red meats I haven't tried them, just remember it is an oven not a grill so you meat will be baked if thst is how you like your steak.
A: the inside of the tube is about two inches in diameter so big stuff needs to be cut up to fit inside
A: GoSun makes a Brew insert that make 14 ounces of liquid boiling hot in about 30 minutes. The GoSun ProPack comes with this accessory. You can also heat liquids like soup or making rice in the cooking tray.