1. Qlikview recommends to have the same major Release running. Meaning, developing on V9SRx and running the Server in Version V9SRx. I've experienced many problems in running 8.5 as Server and developing on V9.
2. You can, but might cause problems as the same situation in 1.
3. Since V9 same Version Number.
4. ? Not using V10 as Server &Publisher. sorry
As someone who has upgraded recently from server v9 to server v10 and desktop v9 to desktop v10 I can tell you that for the most part, any document created with desktop v10 will display and work on server v9.
however there are a couple points to note re using v10 documents on v9 publisher and upgrading evsisting v9 documents.
1) With the introduction of being able to select 32 bit or 64 bit OLE database connection on QV x64, QV10 will insert a "OLEDB CONNECT32 TO " statement which publisher v9 will "fail" on reload. Altering the connect string to the qv9 version will rectify.
2) Mekko charts, chart image backgrounds and table background transparencies created with qv10 will not display on qv9 accesspoint, even if they have the v10 ie plugin
3) I have been unable to edit, add or delete any of the pdf style "Reports" using Qv10 that were originally created with a Qv9 desktop. Thye can be altered fine with qv9
4)On qv10, the syntax checker will regard both "<>" and "-=" as incorrect syntax for "not equals" and underline them in red (despite it autosuggesting "-="). As of QV sr1, "<>" will not work in set analysis however "-=" still works.
5) IEplugin v9 for some reason casues cpu suages spikes when accessing a v10 server
6) QV9sr6 and QV10 IR both struggle to utlise multicore enviroments and a 2 minute reload on a 8gb i5 desktop turns into a 20 minute reload serverside, even on our hugely under used 24core 120gb opteron machine (4 physical cpus). Upgrading to 10sr1 saw the reload time back to normal