On 3), while we are on the topic: Though the activity in variant development increased recently, which is great, I noticed, that all the new variants come with no initial support. This is probably due to the lack of any guide currently available. However, it is really pretty easy. So I will hereby try to change this deficiency:
In most cases you just need to add a folder "interactiveMap" in your variant directory and put the normal smallmap into it, but as Oli said with uniquely colored sea territories, too. This file should be named IA_smallmap.png and that's it.
To make it even simpler you can generate that IA_smallmap.png automatically. For this, just add an "interactiveMap" folder, that is empty (or at least does not contain a file called IA_smallmap.png). When you now call that map through the following URL,
http://vdiplomacy.com/interactiveMap/php/IAgetMap.php?variantID=[yourVariantID],
you should get an auto generated map file that is also stored in the directory of your variant. In most cases it is advisable to do some manual adjustments: As only the area of same color is used for detecting if a user clicked on a territory, you might want to color internal sea bodies like the Bosporus in Con or coastal areas like the space between Danish islands the same as the surrounding land to make it easier to select the territory.
If your sea territories are not selected by a clear border (with no holes!), the auto generation code will not produce a map but an error message that gives you information on the territories that are not separated. You should overwork your smallmap.png in this case or just do it all manually.
Some special rules need additional coding for the interactive map. As a rule of thumb, this is the case when the special rules change orders (e.g. transform rule) or the map appearance (warp around arrows, special unit icons (only if build icons should include the new unit images)). Most code for common special rules can be just copied from other variants, as always.
I try to add the interactive map files for variants from time to time with priority to the popular and big ones. But this gets tedious if you are working on blocks with 10 and more variants so things go very slow. I therefor appreciate your help when creating new variants.