Using @ is completely fine, especially when it is in context, i.e. to refer to someone saying something earlier in the thread. It is also fine when referring to something a user did earlier/elsewhere, for example "I am following the instruction in this blog by @WVFaeryWoman but I don't understand the steps.....". It is bad if you try to drag unrelated people into the thread by spamming your post with @-mentions, for example posting a request for help, and then filling it with @-mentions of the names of people you know gives good help generally.

If people don't like to be notified for @-mentions, they can control it from their notification preferences.

This can happen if you already have the other volcano in your map (because you have placed it at some point). Open up symbol manager (Symbols Menu -> Symbol Manger) and then either hit Purge (will remove all symbol definitions you have used in the past, but which are not part of the current map, or scroll down in the list until you find the undesired symbol, click on it to select it, and hit the Delete button.

As long as line with is larger than 0, it will always be hollow. To get a filled shape, make sure line with is 0.

Easy enough. Started with a clipart png of a cat, used TRACED to convert it into a polygon, then used list on it and extracted the coordinates. Some simple excel magic to convert them into relative coordinates so I could place it where I wanted, and then just created a macro with the SPOLY command that reads the coordinates.

Both of those should be easy enough to do, depending on what products you have.

For the cottage, any dungeon style should do, but Symbol Set 4 do come with Schely's forlorn cottage set, so if you have SS4, that's probably a good option. If not DD3 also works fine. But even without any additional add-ons, you have access to several dungeon styles, such as the Jon Roberts dungeon, or the more limited CC3 dungeon.

The isometric view do require Perspectives 3 to pull of properly. Check the essentials guide to get started, or if you also have the Tome, you can check out the first Perspectives tutorial there.