Hey ragehart, welcome to Dreamviews!
Before I answer your questions just gonna say that I recommend joining one of the lucid dreaming classes here on Dreamviews which can be found on the Dreamviews academy board. As for your questions:

1) Well... Your going to get a mixed response here, personally I would say that once you have had at least one lucid dream via DILD then it's ok to give WILD a shot. But just to let you know it's a tough one and that's why some people don't recommend it for beginners.
2) People have mixed ideas of what a dream guide is, it can be what you want it to be. In a literal sense it can just be a DC that guides you in the dreamworld. Some people decide to take it in spiritual terms, while others say it's a representation of you. The idea is a mixed one, there are some people that might even think it's nonsense.
3) that's a really large grey area... Somebody that tells you shared dreaming is true, could be lying or they could not be. It's just one of those things. However personally I believe shared dreaming is possible, yet I have not experienced it myself. The trouble is that there are two ways shared dreaming could be possible, metaphysical and technological. Well metaphysical we can never prove, not saying its not possible. And technology capable of linking minds... Probably not going to be around in our lifetime, but then again it might so that's why I label this subject as a grey area.
Anyways hope you have a great time here on Dreamviews!