the more the merrier?... you will not get penalized for that.. just not getting as effective... you really need to focus on content.. content is king.. good content attract links.. best links
yes I agree with you that content is the king but we need backlinks too! and we know that oneway link is the best but who will link to your site?? and we also know that social bookmarking site and directory site give you one way link but is it more effective for SEO???
quality content will give you backlinks automatically. People share what they like and you wont even have to worry about backlinking if you host good content. No penalty for backlinks.
no limit until you link to a quality and most relevant site..but nowadays reciprocal links are almost died for google ..they won't help you in a great manner for sure ..try one way and relaxant links