Yes Leffe is a good drink. I wouldn't class it as a lager though, its more of a light beer and yes it is only brewed in Belgium unless things have changed recently, but I don't think so. In pubs they should serve you with in neither in half pints or pints but in its own 330ml glass, technically speaking. The vast majority of Belgian beers are served in 330ml glasses. You should be able to just ask for a Leffe and they should automatically give you a 330ml serving. Drinking Leffe by the pint is a little bit like asking for a pint of wine, though of course it is up to you. They shouldn't be serving you with Leffe in ordinary glasses unless you ask for it. You are well within your rights to refuse Belgian beer if it not in the correct glass if you want.
Most beers are generally better from the pump
if it is kept in good condition. I tend to know where I can get a consistently good pint from these days and tend to stick to the beers that I know are good. For example if I fancy a good pint or two of Black Sheep I know which pub to go to to get a consistently good Black Sheep. Or if I want some good Belgian Ales I know the best place to go for that, etc, etc. I could take you to two different pubs and have hand pulled Black Sheep, one of them will be a fantastic pint, the other very ordinary and watery, both Black Sheep, both hand pull, so the condition they are kept in is very important. One tip is to look out for the blue 'Cask Marque' badge on top of a hand-pull (
http://www.cask-marque.co.uk/find-re...th-cask-marque). In my experience this badge is an almost guarantee of a well kept pint, at least I don't think I have had a bad one when I've seen this mark.
Yes I think Guinness is pretty high up on the calorie intake, a good job perhaps that I don't drink much of it during the heavier drinking season or I would have to do even more biking and tennis to try to burn it off and I'm already knackered and aching all over.
Edit: actually looking at my Leffe glass it is a half pint, so I don't know whether they serve Leffe in half pints instead of 330ml or whether I've got a smaller glass at home. Probably they do serve it in half pints but most Belgium servings are 330ml. I can feel a trip to the Dev Cat Belgian beer section to do some research in the coming week.