(1) I read payoff means the value at expiration. So, if the exercise price (X) = 55, and spot price (S) = 50, then pay off for put holder is 55-50 = 5. Clearly given in Schweser.
(2) The price of an option is the premium paid for option.
(3) Value is option value is Intrinsic value + time value. Time value as per the definition is the premium over & above the intrinsic value. => option premium = time value + intrinsic value? and by this theory, option premium = option value. And through this we conclude option price (premium) = option value? which is also called payoff (value at expiration)?
-----What I understand is these terms are all same at different times and circumstances. Price/Premium means that the value to the option writer. After the buyer buys option, he takes over the option value, which is both intrinsic and time. And finally, upon expiration, this value is only intrinsic, and is called payoff.
(4) And what is profit? I think profit is after subtratcing the cost of premium as well.