Money

Personally, I always use a credit card unless cash is required -- just like at home. Credit cards are convenient, secure, provide fraud protections and many other benefits, cost me nothing to use[1], are accepted nearly everywhere[2], and I earn points for the next flight. It's no different in Ireland, caveats aside:

[1] Overseas, be sure to use a credit card that has no foreign transaction fees (FTF). If your card has FTFs, you'll pay more (often up to 3%), There are plenty of no-FTF cards. Anyone who travels internationally should have one.

[2] Just like at home, almost all businesses will accept payment by credit card. For large businesses, it's very rarely an issue. The smaller the business, the more likely you may find some reluctance/pushback (due to fees the bank charges the merchant), or an outright requirement for cash. You will need cash sometimes, but most places accept cards.

Always bring along more than one card -- one might get lost/stolen, be blocked for suspected fraud, etc. If traveling as a couple/family, bring more than one card in each person's name (if all your cards fail for some reason, your spouse's probably won't be). Credit cards are reliable and safe, but it's nice to not have all your eggs in the same basket.

For cash, your plan to use an ATM to pull cash from your bank account at home is the way to go. ATMs are as plentiful in western Europe as they are at home -- they can be found everywhere in busy, urban places, are more sparse in small towns and rural areas. Check wit your bank/credit union about their fee structure for pulling currency from an ATM overseas. be prepared for the first person you ask at your bank/CB to be completely clueless when you ask this (it may take multiple escalations before you reach someone who can actually answer your questions; front-line CS agents in many banks are often clueless). Generally, your financial institution will charge a minimum of 1% for the foreign currency conversion -- this is actually charged by VISA is most cases; I've never found a place that doesn't charge at least 1%, some may charge more (a good credit union will only charge 1%, find one). There should be no other fees charged by your bank/CU. There MAY be a charge to use the ATM (charged by the ATM owner); that fee should be disclosed on the screen. That fee is per-transaction, so minimize the number of transactions.

Watch out carefully for the scourge of "dynamic currency conversion" ("DCC"), marketed as a "convenience" but really a scammy trick to skim more money from you needlessly. DCC used to be confined to restaurants and other merchants, but now is also present on many ATMs. Always look for a screen that asks what currency you want the transaction to be paid in...always, ALWAYS pay in the local currency; if you don't, they tack on a huge "conversion fee" and give you a loan-shark/mafia style conversion rate for your convenience and their enrichment. DCC is everywhere, watch out for it.

Visa/Mastercard are widely accepted. Amex (and Discover and other more obscure-to-us types), not so much, leave them at home unless you have some specific need and/or know they will work someplace.

Don't obsess over money details, just be watchful. Have fun and stay safe.

Card is easy. Make sure yours are contactless to make life even easier. You could get a few Euros from an ATM in Ireland it makes you feel better to have them.

I was surprised at how much things have transitioned to cash free on a recent trip to the UK. I am assuming the situation in Ireland may be similar. Very little actual cash is needed.

On our Ireland trip 3 1/2 years ago, we mostly used a Credit card - in restaurants, retail stores, car rental - physical businesses. Having cash was still handy, as well - at food stands at a festival, paying our driver on Inishmore island, grabbing a pint at a pub. Cash isn’t a bad thing to have, but get €200 or less from an ATM and then withdraw more later if you need more.

We use a Debit card at the ATM to withdraw money from our checking account - credit cards at ATM’s are way more expensive. The DCC, mentioned above, wasn’t pervasive - it was a bigger deal a few years earlier in Scotland. Just see if the credit card processing machine is offering to give you the “convenience” of ringing up the same in US dollars (at a poor exchange rate), rather than simply charging you in Euros. The sales attendant (or maybe waiter) could ask if you want the sale done in dollars or euros. Always ring up a sale in the local currency, and your credit card company will calculate the exchange rate - not the company running the credit card terminal.