[noman-land]

The act of bidding itself shows interest and raises the price.

[pishpash]

Auto bid raises the price to the second highest price among auto bidders, basically running an instant second-price auction. Sniping avoids running these pre-close auctions.

[celeritascelery]

It does not. Even if you submit a snipe bid the normal eBay bidding rules apply.

[CompuHacker]

The act of viewing the item page in itself demonstrates activity and is relayed to other users; leaking information about, not necessarily intent, but awareness. If you want something, figure out the details without actually clicking on it.