statcounter is a cookie for monitoring website visitor/audience statistics, ie: number of hits, new visitors vs returning visitors etc. Quantserve is almost certainly something similar, if its attached to the bottom of the ET website footer, it'll probably be a cookie that Baron is using to measure the number of site visitors here
Yes, of course Quantserve is just stats picking tool, which is clearly stated on their site, much similar to Google-analytics and such... And to allow it or not, everyone decides... There's always an option to block it or not...
Yes, I don't think it steals passwords and CC numbers... Just picks misc browsing stats such as where users come from, what browser/OS use et cetera...
I don't know about quantserve, but why would you block statcounter? All it does is collect stats...there is nothing malicious.