The sea tools draw on the CONTOURS (SEA) sheet, and are therefore hidden by the land.

You can find the ones you've already drawn by hiding all the other sheets, so you can use the Change Properties tool on them to move them to the WATER/RIVERS sheet.

There are better tools to use to draw more rivers and lakes in the future. Try using one of these two.

It's completely up to you how you group things.

I don't have that many maps to show, but I tend to group similar types of map - like cities, overland, and dungeon, though I do have folders for single projects as well.

I can't remember exactly why I did several shades of dune, but they look ok together. Real deserts are all kinds of colours.

Nice work so far.

It's very much up to you how you develop your maps. I find it quite useful to leave it a couple of days if I'm not sure how to go forward. The moment you open it after a break like that you will know what you want to do.

You could use SCALE. I've just tried it and it works ok. You have to pick the scaling origin after Do It.

There's also SCALEXY if you want to scale the dimensions differentially. You must pick both scale origins with that one.