>>Question 2:
>>Is there a way of not executing the Click() event of an option depending on certain condition?
>

Just wrap anycode you want to execute conditionally in the click method in an if/then statement that checks the condition.
If it is the default behavior that you don't want to execute, then no, but you can make it look like it never happened. You could add a custom property to the optiongroup that stores the value of the group, and only changes if the change is approved by your code. Then in the click event of your buttons, set the value of the group to that value. HTH