It isn't really free worldwide shipping, the shipping cost is thrown into the price. They track your location, if you use a UK proxy then the price is even cheaper. I think the .com and .uk sites are identical.
For time, I think 1 - 2 weeks is the norm from memory. I purchased all of my scott pilgrim books from there and they arrived at different times over a week long period. One did take longer than normal for some reason but it isn't too bad. So your standard shipping time from the UK.
Unless the .com actually ships from the US and not the UK then i'm not too sure on time since i can only talk about the .co.uk website.