Hi Aimei,
For the airfare part, just to share with you that I got my air tix at about S$1,200+ per pax on Thai Airways for SIN-BKK (Transit 2hr) - Paris-Rome - BKK (2 nights' stay) - SIN. I'm going during winter off-peak (before Christmas till Chinese New Year), hence, I guess that's why my tix are cheaper too.
I heard Emirates (or other middle-eastern airlines) are quite cheap also but we didn't check them out ourselves coz' of the transit.
Paris alone is rather easy to plan actually coz' if you read through all the relevant threads in SGBrides, they give you all the answers you'll need in your planning.
1. To get around in Paris, download the Metro map (with attractions indicated) first -
http://parisbytrain.com/files/2008/10/metro_geo.pdf
Takes a while to download, so be patient. It looks very complicated at first look but it's really quite easy to understand after staring at it for a while.
2. Then read Raymond Tan's article at -
http://rtan.net/France/fne.html
I think it is a concise version of everything you need to know. I read through it like 3 -4 times already.
3. On budget, read Raymond Tan's article at -
http://rtan.net/Paris/
Raymond - Hope you don't mind me sharing your links here, coz' they are so useful. They really helped me a lot personally so want to share your good stuff around =)