"With using an ATM, is it clear what buttons to push to withdraw money using a debit card? Do you insert card, enter pin, choose language and then everything is clear from there?"
Yes, except you often choose language before entering your PIN. Don't worry, it's quite easy. And yes, do ask for an amount ending in -30 or -80, so you get at least one €10 and one €20 note. So, if you want €400, ask for €380 or €430 instead.
Convert your bank's daily limit into euros now, and remember (or write down) the number. That way, even jet lagged, you'll know how much to request. The ATM will only ask how many euros you want. If your transaction is rejected, try a lower amount.
But do remember to reject dynamic currency conversion. It can often be phrased in sneaky ways, such as, "would you like to lock in a rate of $XXX.xx?" You want "proceed without conversion." You may then get a dire warning, such as "the rate will be set by your bank and is not guaranteed." Don't worry - your bank will have a much better rate than the one used with dynamic currency conversion.
The rule is, if you see US dollars anywhere in a transaction, it's trouble! You should only see local currency (in this case euros). This never used to be an issue at ATM's, but in the past few years has become much more prevalent.