A one page resume is a foolish idea. It might make your job easier but a 6 page resume shows more details/depth and can separate you from the crowd. Some people will only read page one so making that into a summary page helps but also provides additional depth for those who want to read more.
You can have up to two pages - but ideally aim for one page. I wouldn't go any further than that. You can summarize everything important in 2 pages or less. I would just stick with 12 pt websafe fonts.
A resume is just a cheatsheet about a potential candidate. If you wanted a 6 pager, that's what blogs/youtube/github/stackoverflow you've made/portfolio URLs/etc are for. People don't have time to read a 6 page resume, you would be really surprised how many applications a company gets for 1 job posting (depends on job & company, but it goes into the hundreds and sometimes thousands, not all candidates are qualified though). It takes all but 5 seconds to apply to a company on indeed.com, for instance.
You should have an additional link(s) somewhere on every resume you put, if the person wanted to know more. And you should be using something like google analytics to track that as well. (either link to a specific url+query string and track that, or use bitly/google shortener url)
