Regarding Michaels coupons - yes, they will take them but only for items that Michaels also sells. For example, I was told I couldn't use a Michaels coupon on ribbon because Michaels doesn't have ribbon. Unfortunately, I wasn't quick enough on my feet to remember that Michaels does have ribbon. So, I'd say yes they accept them but don't count on it.
Also, I am signed up for the emails and used the get the paper mailing. I most often use the coupons that come in the Sunday paper, which are valid for that Sunday - Saturday. The ones via email and mail often have longer expiration dates.