I have a question about PR. If you have a site with PR 3 and you trade links with someone whose site home page is PR5 but links page is PR0 would your PR go down?
Don't focus on PR it will only drive you crazy. If you think you might get traffic from that site... if it's relevant then trade.
Linking outbound will most likely not decrease your PR value. PageRank is based on incoming links primarily. Linking to his site will increase his, but you will gain nothing from a PR0 incoming link.
Pages with pr below 4 is hardly going to help you increase pr. But you will alwaus benefit from anchor text and visitors.
Don't worry your PR won't go down, in terms of PR a PR0 incoming link is not very valuable but there are more factors involved to know if the link exchange is worth it. And also keep in mind that their PR0 page could turn into a higher PR page at any moment.
it doesn't matter what is the PR of the links page. It is important that you have one more link pointing to your site. The original PageRank algorithm was described by Lawrence Page and Sergey Brin in several publications. It is given by PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn)) where: - PR(A) is the PageRank of page A, - PR(Ti) is the PageRank of pages Ti which link to page A, - C(Ti) is the number of outbound links on page Ti and - d is a damping factor which can be set between 0 and 1.
Links from pages with low PR doesnt affect your PR. It may give you quality traffic and maybe in time its PR will be higher and benificial to you.