As for the security, not really, in my limited experience. My home town's airport does have two separate terminals, with independent security areas, but different airlines fly from each.
At some airports, all flights will be international (e.g. Shannon). At others, all flights will be domestic or within Schengen.
Some airports are almost entirely used by budget airlines (London Luton), others have very few budget airline flights (London Heathrow).
That leaves plenty of flexibility for how the airport is operated. I'd expect a gate printed on the boarding pass as the larger airports with longer, non-EU flights. I'm not surprised when a Ryanair flight only announces the gate a short time before departure, since they have such a short turn-around time everything seems to be last-minute.
Sometimes if it's far you'll need most of the time to get it. It's this way in London and I've definitely seen it a lot of other places in Europe too.
Depends on the airport and airline.