1. This is along the same lines as receiving W3C “errors”. It’s very common to receive all sorts of notices and warnings when running your site through code checkers. But, unless your site is actually having any problems, you can usually ignore such strict nags.
2. We don’t provide private support, so perhaps this is something that might require hiring a web pro?
3. You may want to check here first: http://wordpress.org/support/plugin/wp-pagenavi