1) It seems to be necessary to have a fleet in both ports to create the depot; rules say only the supply port.
2) The blockade on the supply port should sever supply, but doesn't seem to.
3) Weird behavior of the depot until minor war lapses.
4(?) It could be an open question whether tracing supply from Malmo is legitimate at all, since until the war lapses it's just a sponsored minor. People used to argue about rules like this ad infinitum; the advantage of a program is that it makes a ruling--you can do what it lets you do. But right now, what it lets you do seems to be somewhat, er, idiosyncratic.
1. yes, a fleet in the supply source, Malmo in this case, should be enough.
2. yes, a blockaded port can't be a supply source for the purpose of sea supply(actually it probably could, if the depots filled all other prerequisites for sea supply and belonged to a power not at war with any blockading fleet and there was a eligible fleet not at war with the blockading fleets in either port ).
About 3 and 4
I guess it could be argued that Sweden is not under your full control. Its however not logical in that case, that Malmo could be used as a supply source for French corps, while it would be logical that the Swedish corp could.
Something is definatly wierd with the depot in Hull, it should as per AiE rules not be deemed valid in some cases and not in some. But in a way it seems to be remotly related to the same type of problem that I had in Linz that is described earlier in this thread. And I can see that it from a programers point of view can be a logical nightmare.
I'm not sure I can explain it very clearly without doing a really long post that is very technical something I would prefer not to do, but I'll try
Probably something to do with the order of testing the validity of different conditions and that the program is assuming that if a certain condition is meet its implied that a second condition must be true or false when there is actually one or more situation where this is actually not true. This means that depending on the order of the test or alternativly if it is a positive or negative test you get different results.
Whats complicating the issue here is that France is not at war with Russia so a test of the depot(French) would not be blockaded by a russian Fleet while if you test the Fleet(Swedish) it is very much blockaded.
I would like you to test to move a French Fleet to Malmo as France aint at war with Russia it shouldnt be blockaded and if my suspicion is correct the sea supply chain would be valid.