Which is why I try and get to security 2 hours before departure. I also do a bit of digging online beforehand. Anytime I have flown Heathrow, Gatwick, Schiphol, Newark, JFK etc. I'm well aware that there's a fair bit of trekking to be done.
No, it isn't. Ryanair and other airlines hold batches of allocated gates, they then manage which flight goes where within that allocation dynamically, adjusting as flights are delayed or arrive early. That helps them reduce costs as they need fewer gates to operate their schedule. Ryanair have nothing to gain from people spending longer in the retail areas, they'd far rather people head out of that area as wearly as possible so they might be able to sell them something onboard.
Most airports I know announce the gates a fixed duration before departure, usually something like 1 hour. I'm talking about on-time departures. I don't think the airlines influence this. It's in the airport's interest to keep you in the shopping area as long as possible. As you say though, it's not in the airline's interest.
Yep, it does. Have been on flights where its announced & watched the baggage handlers out the window.
We're talking Ryanair here and that's not how they operate in the airports where they have a significant presence. DAA can only control what batch of gates they are assigned when their overall allocation is up for renewal, they don't get a say on the day.