2 and 3 are perfectly fine. Also, happily use the possibility to take your time playing through possible moves on your wooden chess board at home, or on the analysis board available online at chess.com.
Talking of throwing out: 4 and 5 are not allowed here, people who do so are thrown out of this site 
1 2 and 3 are all allowed under the rules.
The question highlighted is a good one.
I'd guess maybe play as much without any assistance as you can, while training on tactics, then if you are learning an opening, maybe use the opening book up to a few moves while you try memorize it - ie pick your move first then check it in the book.
I don't see you learning much from just copying games from a database.
You can play through those yourself anyway.
I would go for 2 and when you use 3 , consider a move yourself and if the db suggests other moves only play one of those moves when you "understand" (at least put some thought at it) why that move is played. If you put thought at it you learn a bit how to play the opening.
Though 1 is also not a bad idea, but then you have to do a good post-mortem analysis and improve you moves.
Perhaps a combination of both is best.
Hi all, I'm a new member at chess.com and a fairly beginner player -- not sure of my ranking, definitely <1100.
I'm wondering what other people think you should do while playing non-live (correspondence or online) chess, both in terms of ethics and in terms of trying to impove one's game.
Here are some things that I think people can do, ranging from definitely legal to definitely illegal:
Certainly 5 is illegal and unethical, and almost certainly 4 also, but I'm throwing those out there because I expect some people use them.
What about 3? I could see the argument that 3 is unethical as well, because those chess DBs also give you winning percentages of people playing certain moves, and so can be seen as an equally-cheaty recommendation system.
However, I could also see people saying that 3 is not that different from 2 -- reading about an opening in a book or online, and seeing where your current position fits in a variation. Also, as far as I can tell many people consult the game explorer or ChessDB.
I ask this as someone who is usually not confident in the opening game, and is often worried about not playing the "right" thing. Is it better/more ethical to play the game like it's OTB, or will I learn faster if I'm reading about an opening sequence while playing?
Also, if you had to guess, what percentage of players do you think use items 3, 4 or 5 in the list above while playing non-live chess?