1. You're not running a task killer, right? Don't. And do NOT use the stock email client! It is buggy. See this link for suggestions:
http://www.droidforums.net/forum/tec...ange-help.html
2. K9 (free from the market) allows copy and paste. I don't think the stock email allows this.
3. K9 has search
As the link I posted says, Touchdown (another client, not free) is designed to work with exchange so it may be the best thing if you can spend the money. Anyway, the market has a 24 hour return policy so you can at least check it out.