Some quick answers-
Chroma is colorless and there are not colored resource costs. But creatures will only have access to certain spells or equipment based on their own colors, so building a good deck will require you to have good synergy between your cards.
We are giving demos next week at Gen Con and perhaps a live interview feed tomorrow Monday at Twitch TV. We should have updates later on with more screenshots and discussion about the specifics of game mechanics, including the play area.
A match typically lasts 15 minutes. Sometimes it can be very fast, too. Once in a while you can get into a stall match which can take longer. Depends on deck style and play style.
We are launching with 300 cards in the release set.
The 3 strongholds that affect your ability to do things don't have life points, but can only be destroyed after they are empty. So before your deck is actually destroyed, you will get decked out; before your bank is destroyed you will lose all your chroma, etc.
There will be regular updates and expansions. It is a vast game and the horizontal "space" in terms of new cards being invented is very large.
