I would buy all your tickets in advance. Call ahead and ask your hotel to do it. Thats what I did for my train from Shanghai to Beijing. We left from Hongqiao as well.

They'll probably ask for a copy of your passport. Seemed to be a requirement. I stayed in a Hilton and they either wanted the cost charged to the room or paid in cash.

FYI when we got to Beijing, the Taxi line was at least 100 ppl long. Watchout for the scalpers who come up to you and try to get you to go with them and "skip the line." Don't do it.

Customs out of PVG took us less than 30 minutes (not sure how Hongqiao will compare) but it seem to be fairly empty when we arrived. Bags took longer than customs