i was wondering if there is a certain amount of link juice that i lose by having too many links on one single page. for instance, on our homepage we have three different navigation menus that basically link to the same pages. we have one at the top of the page, one in the sidebar, and one in the footer. i personally don't think it's necessary from a usability standpoint, but i also wanted to see if it is harming me as far as link juice is concerned.
If this links point to pages on your site that will not hurt you site. There is something called "Full Mash" where every page is linked with every other page. num_of_links = num_of_pages * (num_of_pages - 1) If many links on your site will help visitors to navigate that is good!
It wont harm your site. I also include navigation at the bottom of my site. I don't want users to have to scroll all the way back to the top to go to another page
It wont matter, 10 links to the same page within your site will only pass the value of one link. However id look at changing your current structure because its totally unnecessary having 3 identical navigation elements. Id change the footer to a simple "back to top" code, then the side navigation to other pages of interest that are important but currently more then one click from the homepage.
google does not suggest you to use no more than 100 links on a page. i think it's the max. criteria for the backlinks