I don't use much myself, but I'll take a stab at a few of those to hopefully help you along.
I found some definition for "class C addresses" but I donít understand what it means for backlink quality.[ I donít know either how to interpret number of "unique C block IP addresses"
This refers to a sites IP address which is the numerical reference on the Internet. Every site and computer has one. They are numbers like 11.345.234
In this example 234 would be the c class. And the more links you have coming from different c class ips is generally considered better. For example, if you had a 100 links to your site from a 100 diverse websites that is good. Conversely, if those 100 links came from a network of sites all hosted together ... not so good. The more unique c block ip addresses the better.
Deep link ratio in percent, im guessing but pretty sure, it is the ratio of links go to the home page versus other pages to the site. For example, do all links just go to a sites homepage or do some go to the home page and others go to internal pages of the site.
The last, not that clear term for me is the deep link ration in percent. Does it mean how deep is the page that gets backlinks?