[daplunk]

Where can I get a copy of the manual without purchasing the game?
It's not available to my knowledge. It is accessed from within the program itself. My videos go into more detail on how to use the program that the read me though imo.

If I purchase the software today, will the upcoming 64 bit version upgrade for free for existing owners of Realm Works or will that be an additional purchase?

There has been no mention of any additional cost and I would make a large bet that would not happen anyway. There would be riots. I'd wager it will simply roll out as the next update hopefully.

Maps and their sizes seems to be an issue, if I link the maps as a foreign object will "fog of world" still be usable?
This should be solved in the 64 bit upgrade. Map's are large files and large files use a lot of RAM. Therefore 64 bit will greatly increase the available RAM which should solve the issue. The Fog for maps only works in Smart Image Objects. The Fog of World stuff will work though as that just flags a snippet as visible to a player if they use the player view.

Can I seperate my data into "separate realms" and open 2 or more at the same time on the same machine?

You can separate your data into different realms but you cannot open two instances of Realm Works at the same time. It's account based so you can only log in once and that account is tied to your windows account which means you can only login with one user per windows accounts. A number of us would love this to be changed but it was implemented this way to reduce any risk to the database due to possible data conflicts.

Does Realm Works handle external monitors internally or do I need to set that up my screens as a multi monitor setup for drag and drop operations to the additional monitors.
You need to configure Windows to use multiple screens and then you can activate which screen the player view screen appears on from within Realm Works. Super simple to use and really effective. Love this feature.