I'm gonna go ahead and say that all my posts should be considered spoiler marked!
In my "proper" ME1 save, it will be an entirely Paragon run with Kaidan dead. I already had one Carth! I didn't need another!
As for mining, if you don't find a deposit, it will still be there if you want to go back. However, I finished the game with over 300k in each type except for eezo which was about 70k, and I had mined maybe half of the planets.