A few thoughts on your questions/concerns:
1. Sometimes, you need more than just a post on the message board. Offer something to start the discussions (at least). In Yahoo, that generates an e-mail as well as putting a notice on my team page. Half of the time, I don't even look at the message board because it's useless babble.
2. Some people don't check their teams/e-mail often so they don't respond to offers. On the other hand, some people don't respond unless they accept it. If you don't like that, then withdraw it. No biggie.
3. When looking at trades, make sure that you see what each team needs and not just the names. A lot of people are saying that Oswalt is a CY Young candidate this year. Trading a stud OF who will get walked over 200 times for a potential Cy Young candidate isn't that bad. Next time, instead of getting upset that you would have offered more for a player, be proactive and make an offer to start discussions.
4. This would upset me. The CCL is there so that people don't get mad and dump their good players. A mistake is a mistake if you drop the wrong guy. It has happened to my league before and the guy just stated the problem and then he picked him back up.
I would say that you overreacted but you live and learn.