We would recommend booking an overnight flight, so that you can land in the morning. While there are some direct flights to Dublin, you will most likely have a connecting flight in London, or New York.
While that is totally up to you and what you are able to do, many of the guests are flying overnight Friday the 13th or Saturday the 14th, and spending the first few nights in Dublin, then heading down to Wicklow for the big day!
While of course all of this does depend on when you will be traveling, a lot of guests are flying into Dublin, staying there for a night or two, and then will be heading to the venue in Wicklow either Monday or Tuesday. After the wedding again it all depends on if you want to travel Ireland a bit or head back home. There are tons or hotels, AirBnB's or regular bed and breakfast options to chose from. If some of the guests want to buddy up with friends to split costs for rooms, car rentals, etc. that would be a great way to save a little cash and have some fun exploring with friends.
For those of you who don't know, driving in Ireland is on the opposite side of the road from America. I would say if you are wanting to travel around, to rent a car. While it does take a little bit of time to get used to, you will get acclimated pretty quickly. Another heads up, the roads are more narrow but traffic is pretty minimal and all of the drivers are very nice, polite, and patient. Driving is a great way to see the beautiful countryside and explore all of the smaller towns. Alternatively, if you don't want to give driving a shot, there are plenty of taxis and ubers to get around, and if you are wanting to venture to the other side of the country, there are loads of tours and buses that can get you wherever your heart desires!
The wedding is located in the Republic of Ireland which uses the Euro. If you are also wanting to head north to check out Northern Ireland which is a separate country, under British rule and uses the pound. You can go to your local bank and they will be able to convert your money before you fly, or when you land at the airport there should be a place in the airport that will convert your dollars. Also, most places do accept debit/credit cards. Also, the dollar is worth slightly less than the euro, the current conversion is 1 usd = 0.88 eur, which will be something to factor while getting around.
There is not a strong tipping culture in Ireland but many locals and visitors tend to tip for certain services, in particular restaurants, and taxis. If you want to tip and are in doubt about how much, think 10%. Warning, watch your restaurant bill, many already add a service charge to the bill and you could end up “tipping” twice.