So to describe the problem, there is a dependent voltage source in parallel with a fixed voltage source, and the control variable is the current flowing in the opposite direction of the current source. If this is to be a valid interconnection, then the voltage sources which are in parallel must have the same voltage. You figure it out.
All three components are in parallel, what does that tell you about what the voltage must be for all three components?
What happens if the current dependent voltage source does not put out the same voltage as the voltage source?
What polarity must alpha be to not cause problems with being in parallel with the voltage source?
In addition to the other suggestions it also helps to review the passive sign convention. That should help with question #3 where you have to figure out the power in the current source.
It gets a little tricky with a source though.
If you have any questions about this feel free to ask right here.