1. Is there a way to play this in a window?
--There are ways of setting a lower resolution, but I too also have problems playing it in a window.
2. I know that crystal is a resource but what is it actually used for if i develop it?
--You get crystal allowing you to train troops with magical equipment... either weapons or accessories.
3. I have found a pasture with Horses how do I develop mounted troops do I put an Outpost next to it to put it within my borders then click it to build on it? or, do I just need to claim and that is all? and they will show up as an option when i design new units?
--You first need to claim the resource by putting it in your borders. You also need to research the tech mounted warfare. Then you must build a stable on the spot to produce horses for your troops. Getting mounted warfare is enough for your sovereign / champions to buy a horse(s) at your shop.
4. Sometimes I will see a red Exclamation over something what does that mean?
--They are just points of interest relating to a notification on the side.
Thanks in advance for any help with these questions....
No problem.