SFI provide us with Ads and Banners for our advertising campaigns. Unless you are a STL you can not use your own ads anyway. You must be a STL or higher before you can have your own ads approved by SFI. Take a look at the ads SFI provides and then you will know what size ads are recommended.
Less is generally better. More or less information can also depend on your advertising medium. Factors like cost and restrictions on number of characters allowed.
