You're never going to get a totally straight answer, because things like voting ring detectors rely in practice on obscurity; if you knew the exact details, it would be much easier to game the system.
Yes it does. You take the good with the bad. You can always ask hn@ycombinator.com about your submission; if it gets a bunch of upvotes but winds up 30 pages down the site, that's a pretty good indicator that something happened.
Yep. I think that's just kind of an unavoidable side-effect of the service offered. It'd be interesting to know the statistics of what sort of stuff gets blocked.
It's probably better to up vote from the feed. When you click on a link from the feed, you're generally going directly to the article. You hit the browser back button to get back to hackernews; chances are if the article seemed interesting, you would then hit the up vote button. When's the last time you hit the up vote button on a comment page?
People have very different workflows, it's very dangerous to assume that the way you use the site is the way everyone uses it. (Probably 90-95% of my article votes are from the comments page, and I never use the back button to return to the front page.)
Almost all my upvotes come from the comments page. If an article looks interesting, it gets opened in one tab, followed by the comments page to see what people said about it. Look at the article, then go to the comments, may as well upvote whilst there.
I do similarly except that I just start with opening comment pages in different tabs, then go through them one-by-one, opening article from the comment thread, and upvoting there if I find it interesting. Saves me on number of tabs opened at the same time, which matters for me because in Chrome, after you hit ~ two dozens of open tabs, the favicon disappears which makes them pretty much unusable.
If I post a link to HN on twitter and people upvote the submission coming from twitter,does it count as a voting ring?