I know this is an old question but nevertheless:
- yes, there are bars open after 11pm. There is no general closing time, each bar has it's own licence (which can be revoked if they or the customers do not comply). If it get's very late and everything seems closed, ask around.
- because there's so many beers brewed in Belgium, there aren't many "international" beers available and they are defenitely not popular. You'll find Carslberg and Corona generally available.
The most well-known beers outside Belgium are Stella-Artois (just a normal pilsner but marketed as a "luxury beer" outside of Belgium) and Leffe (abbey-style).