Currency Question

My wife and I will be arriving In Reykjavik in a few weeks (via cruise ship from the US) and staying several extra days. Do you folks think we need to acquire Icelandic Kronas before we leave the US to have for when we arrive? Such as for tipping our taxi driver and hotel staff?

Also, what is the recognized amount of a decent tip at restaurants in Iceland? We’ve been to Europe several times but this is our first trip to Iceland. Thanks very much!