My questions and i hope someone answers!?

I just watched it and was very confused too.
But if you take some time and try to think about it, well even though it could have been clearer and it was kind of messy, I think the metaphors sort of fall into place... it was just done in such a weird way.
Really the film could have been half as long, and a little more straightfoward, and might've been more successful... the messages seem to be lost to easily on the audience.
I'm still not sure if I liked this movie or not... I appreciate the metaphoric quality and attempt at being "artistic" in that way, but as a form of entertainment it's kind of lost...

You might understand it a bit better if you search it online and read a few of the reviews/articles on it.
Basically it works out something like this...

The "zombies" aren't zombies, they're just sort of decrepit versions of the boys' normal healthy selves... this gets easily very confusing if you're trying to follow it in terms of a "plot" but metaphorically they're supposed to be something like an alter-ego or the "gay" side or feelings of the boys.
Nicholas isn't necessarily gay, but he has curious feelings for sure, as many boys may feel at one point as children and have a "gay experience" or experiment, Nicholas is just far more apt to follow his feelings on this path than his friend Bobby, who we see might be curious too (there's a little of that "tension" with them in Nicky's fort) but ultimately desires the girls (plus it's the norm in society, of course!). I got the impression Nicky is mostly shy. He also might be gay except for his fear of showing that side of him (which he hides until near the end when he's caught with the zombie Bobby by his mother, and we see her disappointed and his "sickness" comes out and is visible). The metaphor is that homosexuality is a sickness and thus that alter-ego or side of those characters is portrayed as diseased. This probably has less to do with any commentary on whether being gay actually is "sick" than it does with how society views it, as something "wrong" with the person who experiences these gay feelings. The "gay" (zombie) version of both boys say, "don't look at me" or "don't look at me like that", especially when Nicholas says it to his mother after she sees he's been maybe acting gay (*gasp of shock*); the way she seems to look at him is different and Nicholas dislikes the way he's being seen now. I think those lines are very indicitave of the metaphor of how homosexuality is "seen" as something wrong.

The movie is about sexual identity. Quoting the films director/writer, Jeff Erbach:
"It's not really so much about being heterosexual or homosexual, those are polar opposites, but sometimes things exist in between. Sexual identity is sort of on a sliding scale and I don't think anyone is ever really 100 per cent either/or."
I think that quote is interesting because in the movie, once Nicholas kisses Bobby and we begin the very metaphoric and confusing turn, the characters do seem to go in very opposite directions. Bobby splits into his heterosexual self (somewhat more macho, seen with the bat a lot, and there's no more of those tender moments between Bobby and Nicholas like in the beginning when Bobby does up Nicky's hair) and his homosexual side, but then there's nothing left in between. It seems to come down to a harsh choice between what a boy should be, gay or straight, with no room for intermediate feelings; mostly I think due to the negativity surrounding the gay option (I mean, obviously that isn't the option to choose - to be sickly and unappealing and looked at strangely).

This isn't a conventional movie where the more bizarre parts can be easily explained as "imagination" or in Nicholas's mind. In this case there is less to do with a coherent plot in the conventional sense and what characters do and more to do with the emotional quality and moods, and who the characters are, largely acting metaphorically to create a different sort of plot.
Nicholas and Bobby are both dealing with their feelings and what happened. Bobby chooses to reject his gay feelings and wants to kill/get rid of that part of himself, but Nicky wants to hold on to it and keep that side of Bobby because that's the side he wants. Both are real parts of him and are also made real people (it's not exactly based in reality).

The father is a bit more complicated. He's controlling, even from beyond the grave. He represents something like the dominating masculine values - "like girls. Your gay side must go away" sort of stuff. He manipulates and controls and pushes Nicholas, including at the end where he follows him, ready to control him more - like girls! - if he ever slips up. He takes the gay side of him away and puts him away, saying something like "we all leave it behind" like leave those feelings or that part of us behind, rejecting altogether (in that very masculine way) any feelings we might have that aren't the right kind of feelings.
Nicky isn't really "not gay" anymore, just sort of forced to put away that side of him and keep it locked up.

It's a social commentary about what society thinks, I think mostly. There seems to be a lot of those themes in that vein. Something about the acceptability of expressing your feelings and what those youthful experiences can mean to people, and just how hard and confusing it can be... the fact this movie is somewhat confusing is just another reflection of the more metaphoric type of plot. Quite well done overall, a good artful film.