1. Seems reasonable to tie the two. If it were different slides, it will be just addition to difficulty, but tied togather give players choice of playstyle.
2. Empire building is a must. Without it it is no more 4X, even assymetrical one. For me it feels almost ok now, but a little bit of additional city spaces (or ability to create them via spells, quest, etc) would be nice.
3. Expansions are great, but it is too early to speak about them in any level of detail.
4. -Magic concentration. Less crystals, but each is stronger. And the other way around.
- World difficulty. More strong monsters, but these monsters have more goodies. And the other way around.
- Minor race activity. They will send more troops and overall help to their allys. And, you know.
5. Reciept or ingredients for AMAZING item can be rare to find, making it on par with just finding the item. I see no need of restrictions here.