Links don't really matter, we have one on all our answers. It's answering a lot of questions in a short period of time, combined with the fact that you have links, that is getting your account banned. We've been doing this for about four years and always limit ourselves to a maximum of five questions answered per day. We also don't answer questions everyday, and when we do post answers, we try to be as informative as possible (everyone know's that answers on Yahoo are pretty brief) in order to try to get the votes for Best Answer. This will help your account not get banned as well. Voting on Best Answer on other questions that you are not answering is always a good idea.
Not entirely true. If you spam and get targeted with just a few answers, your account still be banned.