Hi Stuart,
If you’ve never been in Amsterdam and only have a few days, you’re going to have a great time just strolling around the city. There’s plenty to see, and the streets, old merchants houses and canals are quite a site for anyone who did not grow up with that. Also, Amsterdam is a great mix of people, it’s great just to watch people (after all, the west of the Netherlands is one of the most densely populated areas in the world.)
Of course there’s plenty of art, and if you like that I can highly recommend the Rijksmuseum (with Rembrandt’s work, including the famous Nightwatch) and the Van Gogh museum. These two museums are practically neighbours.
There are also some outdoor markets, which I like to stroll around on. There’s one on Waterloo Plein - selling clothes, jewellery and anything else you couldn’t think of selling on a market.
Then there are some outdoor food markets, which are great just because of the vendors shouting their advertisements 
Never been to a session in Amsterdam…
Have a look at this site: http://huizen.dds.nl/~eltjot/celticnl.htm
It lists some Irish pubs in Amsterdam under ‘Locations’ (look under 'Noord-Holland, which is the name of the province Amsterdam is in).
If you’re lucky and the weather is good (is possible early march), there is the possibility of taking a boat trip on the canals. It’s a unique way to experience the city. That’s about the only touristic thing I would recommend. Steer clear of plastic tulips, miniature cloggs and the like.
Since you mentioned it, also steer clear of pott; it turns you into a vegetable 
Now Indonesian food - oh, yeah - do I miss that!
A good Indonesian dish and a genuine dutch brew to extinguish the spice fires (steer clear of Heineken and Amstel beer - go for Grolsch). I’ll be in Holland for a few days mid february - guess what I’ll be having for dinner…
Have a great time, and let us know about your experiences.
Cheers,
Jeroen