Ya you can put up your website link on footer section but make sure your link is not repeated more times on website page if repeated than you can say it's harmfull for your website..
Yes, you can put your Website link in the Footer section, but make sure it is not repeated in your site, other wise it would look like too bulgy, I mean it looks over optimised.
Footer link is very useful for users to go on internal pages. You can use these and these are also helpful for search ranking.
Yes you can but not in huge amount. Footer section should contain only Main and useful pages of your site. E.g. Home | About | contact | Services | etc.
You can use main page links, do not repeat many times, Do not hide text (Must be clear text), Do not give links for every pages. Dont use many colors on footer.
If you are talking about external links - it's 2014 and you are asking this? Where have you been the past several years? I suggest you read through a few years or posts on searchengineland.com and seroundtable.com and get up-to-date with the dumb ideas to avoid. If you mean internal links for your site, it's not the best navigation area and should be used sparingly. Take a look at some of the big ecommerce and news sites, for example, to see how they do internal linking from there. Take a look at: http://moz.com/blog/footer-link-optimization-for-search-engines-user-experience