Freight despatch is not an issue, as if weekends turn into a two-day format this means that they can afford to arrive one day later than they do now.
They would still have to fly out at the same time they do now because if you have all the support categories out on Friday the F1 teams would still need to be setup on Thursday so to not disrupt the support categories running through Friday.
I personally think 2 day weekends would be the wrong thing to do as it would be less value & less F1 running for fans attending the event to see.
Additionally it would actually put the smaller teams at a big disadvantage because several of them don't have simulators & dropping a day & 2 sessions of running would put a larger emphasis on using simulators to get a baseline setup before arriving at the event. The bigger teams already hit the ground running because of that but with the practice running they have the mid-field are able to catch up & they generally go into FP3 more or less on-par with larger teams in terms of setup/car balance.
I've always felt the way to look at Friday practice is that its a test session for the teams & as a result i've always felt that they should not be forced to run. Friday practice/testing & the practice sessions in general are there more for the teams benefit & not so much there for the fans.
As to Saturday races, Reverse grids etc... No & No!
With regards to bringing back the Warm-Up, I'd actually rather they didn't because Sunday mornings are better now than they used to be because we now get 3 races from the support categories which I find a lot more interesting than a half hour F1 session where nobody was really pushing all that hard. Its also not really needed now because of the parc-ferme rules & the fact that even without those with the limits of engines/gearbox's etc.. they wouldn't be changing everything overnight like they used to so there would be no reason to run on Sunday mornings.