Don't ask people to do your homework for you. These are really basic questions. If you googled you would find the answers. Have you even tried to read your textbook? Have you even read the questions? If you don't know what efficiency, power, current and voltage are, it's pretty hopeless. Sit down and think about what efficiency and power mean. And then think about what voltage and current have to do with power.
Read the word "Gain Bandwidth Product". The word itself is describing to you EXACTLY WHAT IT IS, as is every other definition in the questions.
Perhaps you should actually read the question and think about it? Use common sense. These questions are intuitive enough that if you just guessed what the equations might be, you would probably get it right. If we give you the formula, we basically did the problem for you- that's how simple it is.
Put some effort into your work. If you can figure out F=ma means anything to you, you can solve these problems.