Can the options be excercised early? and if so does that affect the excersie price? I thought options can only be excerised at expiration?

American options can be exercised anytime through expiration. European options can only be exercised at expiration.

It does not affect the exercise price. But it does affect the value of the option. The price of American Options will always be more or equal to the price of European Options, bcse of the advantage of being able to exercise them before expiration.

All things are possible. You can certainly have an option with varying strikes depending on exercise date. An example would be a bond callable at 102 in 2 years and par in 3 years.