1) & 2)Yes you can.
The advantage is that you can freely distribute your mde to whoever provided the target computer has installed a runtime version of 07 or 10. 07 and 10 runtime versions are available for download free of charge to anyone see 07 link at bottom (03 runtime versions are not available freely). If the target machine has Access either 03 / 07 or 10 I recommend you do NOT install any further versions of Access runtime or otherwise. For a start you shouldn't need to as your mde should work anyway. My personal experience is that machines tend not to like multiple versions on the same computer.
03 Mde's require a version of 03/07 or 10 so some version of access is required on the target computer.
3) My personal experience is that it is not a great idea to have multiple versions of access on a single machine. I haven't used runtime installations at all but installing Access 03 after Access 07 causes office to do a mild re-install of the particular version of access anytime you swap between versions of Access. Additionally if you installed Access 03 after 07 then the re-install doesn't re-install the MS Access object library correctly and your event handler can stop working. It doesn't change the reference back to the .11 object library keeping at the Access 07 .12 library within the registry. Interestingly the event handler still works if 07 was installed subsequent to 03. But you still get a nasty "office is re-installing ... " when you flip between versions.
As I have said not used the run installations but they are almost full versions of access with menus turned off so I suspect you might get issues if you had one full version and say a runtime later version. Hence my recommendation not to install additional runtime versions.
Using a mde from a normall full version of Access just means that the instance of Access you open behaves as if its runtime. Users will not be able to alter any of your code or see any of your code in the mde despite the fact that they have a full version of access although they can create their own projects in the normal fashion.
Practically speaking though this should only be an issue on the development machine as there is a temptation to install multiple versions so that you can check that your application runs in the differing versions. I would recommend you keep your development machine on the 03 and only upgrade when your lowest user has moved away to 07 ( if you like 07
) - which sounds like it might be awhile
Access 07 Runtime download
