In the movie,Is Alec gay?

yes, I would think so as he is in the amazing book. :)

Yup.
*Movie spoilers*
Alec confronts Clary, just like in the book, and she says something (can't completely remember) about Alec being nasty to her just because he's in প্রণয় with Jace.
Also, I প্রণয় the scene at Magnus's party- Alec's reaction. That awkward smile Alec gives. I had to physically stop myself from squealing দ্বারা putting my hand over my mouth.

In the movie he is he

yes, in the movie alec is xx