Not really related to crashing, but that image of yours isn't the best to trace. You don't really want those narrow rivers represented as holes in your landmass. Same with lakes really. (There are some advantages to doing it that way, but in general it complicates things.)

Honestly, I am a bit confused about that image, my mind can't really process it. If the white is water, your landmass in black loos really odd with those straight water section north and south, and if the white is landmasses, then what is the white lines? But in general, when you are using traced, you'll want to start with just the landmasses. Ocean and rivers can then be made as a separate polygon in a separate pass.

That's more a question about how you use the files as the file format itself. None of those files are merged by default, they keep their layers, so if a layer contains a single symbol (or multiple symbols but spaced out from each other), it is easily extractable from the file, but if the layer contains multiple overlapping symbols, then they aren't isolatable anymore.

Of course, if you merge all layers/flatten the file, then it isn't an issue, but that isn't commonly down with the file in those format, you only provide a flattened export when exporting to a common image format.

Due to the way fill styles are defined on a per map basis in CC3+, old maps won't automatically have new fill styles.

Use Draw -> Insert file, and pick a new map that does contain the style. Now, with the map to insert on your cursor, simply hit Esc, and the fills will be inserted, but not the map itself.

You can still use html if you switch to the Wysiwyg editor. If not, you'll just have to put the hi-res link below the image instead.

My advice, learn and understand the techniques described in both, and use what's appropriate for any given situation. I've also got a blog article here, but it basically uses mostly the same techniques from the Tome.