The CTR is absolutely normal. I have come across with people reporting about 5% CTR. So, don't worry. Keep cool -Dairyman
I have many sites with 50% sometimes %150 or %200 CTR no had problem for two years.. absolutely fine. (under 5% is very low for me )
Yep, that ctr is totally normal, in fact you even may raise it a little bit more (better add placement?)
May I check the quality of your site. You may PM me your site. No spamming. Just to check the quality of your site. And build up
3% ctr with a big number of visitors. wow. impressive. I believe that would not be a problem as long as no illegal click, nor attacks are recieved.
Your CTR is ok. As for the changes google gave you, it's best to follow it. If you want tips for increasing CTR then read my thread. http://forums.digitalpoint.com/showthread.php?t=2112142 As for putting tribalfusion or any other ad as long as it's not the same with the adsense layout you will be ok. I've done putting adsense and adbrite together and it was ok.
As long as your traffic is legitimate it shouldn't be a problem. By legitimate i mean, not paid 2 click programs and traffic exchanges.