To beat 1 or 2: Click into post, upvote, go back
To beat 4: Open in tab, leave open, vote later

The other problem with 4 is short posts. If someone posts a funny meme or a couple pictures, for instance, that takes a lot less time to "read" than a few paragraphs of text.

Not against these ideas per say, but the reality is users will generally find a way around.

Isn't 3 already the case?