Koendd already put you nicely on your way I see, thanks for that Koendd!
In the war heritage we have in Brugge the battle of the Flemish against the French in the middle ages, the very nice second world war bunker museum in Raversijde with some unique pieces there, the battle of the Ardennes in Bastogne in the second world war, it was the last big offensive of the Germans.
The city of Brugge has very nice architecture, it's just a very very lovely city, In Brussels you have the big market, manneke pis, the atomium building, the royal Japanese garden, and so much more.
You have the lion of waterloo where Napoleon ( the big French conquerer) lost his last battle.
And the only waterfall's we have are the waterfall's of Koo, but there not so big... :-))
these sites should give you a lot of information about the cities and places you can see, there's a lot more where this came from.
About traveling in Belgium this site is what you need, it is the English version of the foreign affairs in Belgium.
All the info should be in there. Try to inform about traveling with your baby, and what you need. (vaccinations, visa's, and all that) in it's not in there sent them an email with your questions, it can take a while but they will answer it. all contact info is on the site.
If you are from India, the weather will be cold and you have a big chance on rain in Belgium, so be prepared.
I can't place a timetable on the weather here, it's varies to much... unfortunately...
For the accommodation, you can go as far as you want. Low prices I suggest you seek a youth hostel. all other hotels will be very price. These site's will help you.
About public transport, is't true it won't be cheap, prices are quit high in Belgium, like in whole Europe.
A nice fact 2 know is that Belgium was the first European country to have the railroad in the european continent!!!
trains in Belgium: http://www.b-rail.be/main/E/index.php
Bus: Flanders: http://www.delijn.be/ (sorry no English version)
So that covers it I think, if you have any more questions... just let me know!
Have a nice trip!!!
Bye the way, maybe you can help me with information about India...