Because java byte code is the same on all computers, compiled java programs:

no. when the asker posts the question they can make a question worth what ever they think is a fair price. although it must be within the limit of the points they currently own. 5 is the minimum number of points a question can be worth. if a question is complicated or has lots of parts to it, it is better to make it worth more because more people will be more willing to answer.

hope this !

that without the operating systems you would have to control and synchronize computer hardware.