Advance ticket to/from Bruges

No need to get them in advance. There’s no savings in advance tickets, at least when I was in Belgium in 2023.

No, no need. Tickets never sell out, you can buy them at the station or on the app on the day of travel. No advantage to buying early (except for your own peace of mind).

Lavandula

and no reservations possible. If you download the SNCB app, you can purchase a ticket a few days before, or once you land, and simply hop on the train and go.

Do note, as long as you avoid any Eurostar train, or the Eurocity Direct trains, you are buying a ticket for that route for the day. Even though it may look on the app you are buying for a specific train, you are free to use any train that day, on that route, you may even get off, look around, and hop on a different train.

There are some direct trains to Bruges from the airport, but I would not wait long for one of those, otherwise you will change trains at Brussels Midi/Zuid.

If you were thinking of doing a bit of sightseeing, getting off at Brussels Central, or maybe Ghent would be an option. There are storage lockers at both.

you may even get off, look around, and hop on a different train

Absolutely not. That system doesn't exist anymore.

It is not permitted to interrupt your journey and continue it later.
Connections are of course still permitted as suggested by the journey planner.

For an official reference, read here https://www.belgiantrain.be/en/support/faq/faq-routes-schedules/faq-choose-your-route

'With a ticket, can I interrupt my journey?'

I flew into Brussels in 12/23 and waited until I arrived to buy my train ticket to Bruges. You never know if your flight will be delayed.

I see that there are multiple departures on a daily basis.

multiple departures on an hourly basis