I.m.o only 1 & 2 are really needed, but some of the small ones are worth to think over too!
1. Making it possible to bann heroes and units completely, perhaps even some artifacts. Heroes and artifacts - I understand if many disagree, but the units - instead of forcing the player to edit every single castle on the map to ban medusas, the designer can do it by opening a menu, and once and for all get done with it - perhaps there could be a choice between "total bann" and "no productions, but available in ruins and from hero offers".
Heroes, I don't see the reason why not to get the choice to bann them. It's the map maker that makes the map, and he/she doesn't force others to play it. No really, some maps would only gain in not allowing ex. barbs and assas - not all ofc, but some. A lvl 3 assa can fly and has 108% chance to kill the enemy... For some maps, it's not worth putting points in personal ambush, but in a few small ones, they and babas wreck the overall balance - almost like you have to choose assa or baba or loose. I doubt hero types will be banned for no reason and belive that adding a function like this only would improve the game.
Artifacts - as above but, you know, no arguments for it. Why not? If the map makers does the map, he/she should be free to decide which items should be available. I don't think it would be an important change, like the two others, but a small change to the better. Some mapmakers could probably make good use of it.
2. Adding short buttons for different terrains. R for ridge, M for magma, R for river, W for water - etc! Would speed things up greatly!
Some small things:
Add a "redo"-button? (I would use it often, don't know about others! )
making it possible to use the old bridges. The new bridges (not the small ones) are quite bombastic, i.m.o, the old ones blended in better, but the new ones works better in some places.
If you out an item on the map and then click "undo", the item is gone and can't be found in the item list. It's gone. You have to load the game again to be able to get it again. Only way to remove safely is removing with that "edit settings"-button.
1 square water terrain, why does the smallest have to be 4? 1 would be great!
You place a group of enemies on a couple of artifacts and then place a mine or watchtower/etc on them. Then you think, "ah, i forgot to set income to 50" and try to edit settings on the stack. But first, you can only edit artifacts. You have to take them away to be able to reach the units. Then you have to take them away to reach mine, set to 50, and put out units and artifacts again. A "edit which group?"-window would help a lot!
mini map is very big on 125 and 150, it blocks part of the screen.