Yes and no. See, there's the aspect of using a walkthrough just to get past the game. That's cheating. But, if you're hardpressed to do something and a walkthrough is pretty much necessitated, I see no reason at all not to use one.
No, not at all. If you're really stuck somewhere and have no clue what to do next, there's no problem with getting a little guidance. But using it the entire way through without even trying for yourself isn't really cheating either. That's just you sucking the experience out of the game.
Personally, I don't like using guides unless I'm really really stuck. But that doesn't mean that I resort to them too easy. I like trying everything I can first or just skip it and get back to it and if it still doesn't work then I'll use some guidance. It's really cheap to just give up too easy and have everything spoon fed to you. There's no sense of accomplishment that way.
No. It's like eating junk food: a little is okay but too much isn't. The only way to cheat on a video game in my opinion is to use a cheating device in order to complete a game or to use a walkthrough so much that you're not even trying.
Also, I'd say it's okay to use a walkthrough for unrequired "100%" items like the Gold Skulltula Tokens in Ocarina of Time.
Well the purpose of the game is to enjoy yourself so if using a guide enhances your enjoyment of the game then you'd be cheating yourself by not using a guide. Cheating can only really occur if you are competing against someone else. Since Zelda is nearly always a single player game, the only way to cheat is to violate any rules that you set for yourself or that are used to compare your performance on the game to others' performance. For example I mean that if you and your friend agree to race to beat SS first but say that you can't use a guide, then using the guide would be cheating. IMO the idea that using a guide in of itself is cheating is ignorant of what the word cheating actually means. Cheating does imply dishonesty so one way to cheat involving a guide would be to beat a game by using a guide and then telling everyone that you beat it without one.
I think it's mostly a personal preference. For me, I will do my best to not look at a walkthrough my first time playing a game (and I can be stubborn -- I've been stuck for weeks at a single point in a game and still refuse to look up the solution), and then on my second playthrough I'll use a guide to get everything I couldn't find myself. Other people who aren't as stubborn/hardcore might not have any issue using a guide, and still get just as much enjoyment from it. Like I said, it's individual.
I would say that it can be cheap, depending on how you use it, but it's not necessarily ever cheating. Even if you look up what you need to do to progress, you still have to do it in the game, so it would only ever be cheating in something like Professor Layton where figuring it out is the whole point of the gameplay. Even if it's not an entirely puzzle-oriented game, though, I wouldn't say it's very classy to use a walkthrough all the way through a game. If you can't for the life of you figure out what you need to do, then by all means look it up, but for the most part you should try to figure it out yourself. The first time I played through Twilight Princess (I was only 12 at the time), I had a walkthrough that I followed religiously to lead me through the game rather than figuring ANYTHING out for myself, and I regret playing through the game that way. It's been a while since I played it, though, so I should be in some ways going fresh into it when I replay it before starting Skyward Sword, and hopefully playing it the proper way will help redeem myself in my mind. >_<