Evaluating Agricola as a 2 player game: how long would it take, how competitive is it, complexity, etc.
Agricola is an excellent two-player game. In fact, I find that I prefer the two player version of the game to higher numbers of players. I originally bought the game so I would have something less aggressive to play with my wife, and it works brilliantly for that purpose, both because of the game mechanics and because the theme is quite peaceful - Agricola is about building, not destroying or dominating.

It does take about 30 minutes per player, so yes, around an hour to play once you've got the hang of it is a reasonable estimate.

Agricola would probably be 'occasional aggression' on your scale. You are mostly concerned with improving your own farm, but there's a strong strategic element where you consider what actions you need to perform before your opponent. Usually it's more about making sure you get what you want, rather than deliberately trying to make your opponent's game harder, but you can definitely play it several ways. I know one friend who likes to try and deny animals to the other players, and constantly picks them up, even when he doesn't need them. What you tend to find though is that this type of behaviour is sub-optimal for your own game. In other words, if you concentrate on making your opponent's lives harder, you will have a tougher game yourself, because in general you will make less productive actions.

Agricola is quite a complex game, if you play the full rules with the occupations and minor improvement cards. Your first few games will probably be quite overwhelming. I would rate it as a 5 on your scale without the cards, 6 with. It's as complicated as Arkham Horror, but in a different way. The rules are much more precise, in my opinion, so I found once I'd learnt the game I very rarely have to actually look anything up.

Agricola is a pretty deep game. There are many different strategies, and one of the best features is that the random cards you draw each game often mean you are incentivised to play a strategy other than your preferred one. I have played Agricola hundreds of times, and it's one of the very few games in my collection that I don't really get bored with. It's much more strategic than Carcassonne or Settlers of Catan. However, no game I know is as deep as chess, so I guess that makes it a 4 on your scale.

Summary: If you like interesting board games, I don't see how you could not like this. There's a reason everyone loves Agricola. And for the amount of replayability this game holds, I think it is excellent value for money.