If we choose to surcharge, do we need to apply the surcharge to all transactions? 

No, it’s up to you what transactions you apply the surcharge to.

For example, you can either apply it to all transactions or you can choose to only surcharge on transactions that fall under a certain value or apply it to a certain card type used.

You must also ensure that you notify the cardholder at the time of the transaction and that you also have signage up informing customers of the surcharge amount.