It depends what you are going for. To create a top-down overview, any city style should suffice, you'll probably be mostly using the house tool to create your own shapes rather than using finished building symbols.

If you're looking to map the interior, dungeon styles will allow you to do that. I think you're probably be best off with a regular dungeon style, the Castles add-on will probably not give you too much for a magic scool, other than perhaps some castle drawing techniques, but in general, you'll probably enjoy a modern bitmap based artwork dungeon style more.

If you are after the perspective views, then Castles may help you a bit, but it is probably better to start out with Perspectives 3 instead. But a perspective view of such a building is going to be a complex task, so not a good starting point for an inexperienced user.

You talk about floorplans here. Did you create that using the floorplan tool from a city map? Did you perhaps pick a floorplan template for a style you don't own?

Try the print Wizard. Right click on the print button or find it in the file menu. It guides you through setting up the print, including multi-page print.

Do you mind sharing the .fcw with us so we can have a look?

You can also try using the "Rectangular jpg" save option instead, and try to just export a small part of your map. Does that work?

Yea, I think the first option for each product should have gotten you the right installers, but generally, what you should be looking for is if there are separate download links for the CC3 and the CC3+ version, in which case it is important you get the CC3+ one, the installers for CC3 will not install properly into CC3+.

And yea, getting the monthly content installer is good, it contains extra free stuff.

Now, make sure to install the base product, CC3+ first, all the others (except FT3) requires it.

Now, as for products installing things other than in program data, this is optional. Many of these add-ons allow people NOT owning CC3+ to install them just for the artwork, and in that case, it will install that artwork into documents. There should be a checkbox to just turn off installing that extra copy altogether during the installation. Just turn it off, and it will just install the standard copy for use with CC3+ in the ProgramData folder.