For credit cards, yes make sure you let your bank know you are going - in fact call at least twice to double check. They may still get it wrong and put a "fraud alert" hold on your card until you call them personally - so bring their non-800 phone numbers (I think it's okay to call collect). We didn't bring a chip and pin credit card. We only missed it in automated places, Barcelona Metro and gas stations, because we couldn't use our regular mag stripe cards there. I always take a primary card and a back-up card that only gets used in an emergency.
For ATM's. I use a debit card for cash but nothing else. Same rule for calling your bank ahead and having their number available. Same for bringing a backup (preferably an account you can transfer money into from the first choice account). I use an indoor ATM unless absolutely necessary. There is plenty of fraud in Europe associated with ATMs and there is less chance an ATM has been tampered with if it's inside a bank, grocery store or department store than out on the street. Normally there will be a warning to cover your hand when you type in your pin, this is to counter both someone observing your pin as well as tiny overhead cameras put on the machines by thieves. Keypads are in numbers only, no letters, so use a four digit numeral pin or at least know the numbers associated with your pin. If anyone is standing uncomfortably close or offers to help with your transaction, cancel, take your card and find another machine elsewhere.
Don't choose to have a transaction in US dollars anywhere (hotel, restaurant, car rental, department store). If you do, you will be charged two foreign transaction fees. One by the merchant/ATM and again by your home bank.
I think 100 euro a day is pretty comfortable for walking around money for two people. I keep it in my front pocket, or we carry 50 each, and everything else stays in a moneybelt. If you need more, use the restroom to access your moneybelt/equivalent, don't take money/credit card out of your moneybelt in public. Every time you get into your moneybelt, take a good look around to make sure you didn't drop anything before you leave; remember this is the stuff you don't want to lose.