Yes they will (most of times). One thing to remember: Taobao is entirely third party sellers. Nothing you buy come from Taobao itself. So from item to item, the terms vary quite a bit.
mostly, but I don't think all?? The TMall section is large retail stores - it's the equivalent of buying from a large high-street retailer. Some of them are shipping thousands of packages a day, so you can place some faith in them (ie. at least 110+ stores made more than 10million RMB in a day, so it's not like buying from a street market trader.)