Should I set up standard email accounts? What are they?

There's no reason to create them all as individual e-mail accounts. You can just set up forwarders that lead to a generic site.admin@ account and set up a filter for that in your mail client to keep the noise isolated.

You'll want them, because:

• webmaster@ is where good natured people do things like report broken links, it happens more than you'd think!
• abuse@ is nice to have, it sometimes keeps people from going directly to your host / data center / bandwidth provider in the event that someone found a way to use your server to send SPAM.
• postmaster@ is handy to check, and make sure root's mail is also sent there, at the least it will show you if your mail server is configured incorrectly, it will also catch bounces that let you know you have a spammer.
• hostmaster@ is strongly recommended by RFC2142 as a well-known mailbox name for your DNS zone's SOA record.

I usually check my 'catch all' once a week and clean it out. It only takes a few minutes. Once in a while you find a real gem, which is something like "Your site helped me, I just wanted to say thanks for the resource!" .. which always makes your day :)

This, of course in addition to the convenience of automatically generated SSL certificates - SSL providers will send confirmation email to one of the above addresses, so you need to be able to receive it.

Every RIPE LIR (Réseaux IP Européens Local Internet Registry) must have an abuse@ account and based on the RFC 2141 the webmaster@ (http), postmaster@ (smtp) or hostmaster@ (dns) addresses are used by most (all?) Providers.

So if you don't want to be an LIR and don't use certificates, you are mostly free to set your mail addresses any way you want.

If you plan on purchasing a domain-validated SSL, admin@ is generally a good one to have, as the domain-validated certificates use a small list of hard-coded email addresses, and admin@ is generally one of them.