I have 10 years experience in IT, English speaker.
I have also worked as an architect for 5 years.
I recently did a similar project for a Uk client.
Furniture layout on the web can be done using the new Canvas properties of html5.
It will only work on current browsers, but will work well and be easy to extend
You can also do the whole thing in #d, using the new webgl standard. This agin will onyl work on the latest browsers.
If you look at the % of users that have the latest browsers alwasy its very high. This is because the browsers autoupdate themselves these days.
Anyway hope to get a response.
Regards
Gerard