Trade Assurance is quite misunderstood and far too many won't ask, rather they make assumptions with guesses & theories and come up with "conclusions" base on that bafflegab.
When a Client orders something via Alibaba, the vendor is not paid until the packages are delivered, Alibaba holds the funds in "Escrow" until delivery is signed off. So the vendor is OUT OF POCKET till everything is signed off. This makes some quite aggressive (warning flag BTW) while others (more honourable) are not.
Regardless, Credit Card or PayPal (incurs extra fees) but accepted now that they have an official presence IN China (new this year).
Shipping Dates & Times CANNOT be Guaranteed by ANYONE, ANYWHERE ON EARTH ! Covidus Interuptus Effect, everyone is suffering that and completely outside of anyone's control. You will NOT get a Hard Delivery Date Commitment... NOT EVEN With Air-Express Freight ! (I use that a lot actually).
There a FEW (not many) Vendors who've proven themselves repeatedly to be honest & reliable with definite integrity and TT Direct Transfers with them is fine (and it can save time & hassles for everyone as well, AND that also get's held in "Escrow")