I haven't seen the film you mention so I cant comment on that. I have known several members in good standing who were homosexual and who held church callings and attended the temple. Mormons, in the UK, approach things in a don't ask manner however, since all members are under the same 'law of chastity'(basically no non married sex)this poses a unique challenge. Mormons of course do not accept gay marriage. This denial of the right to marry out of desire has been the storm that has sent many lds gay men into depression, suicide and misguided straight marriages. At its most extreme the church sponsored some pretty immoral aversion therapies as well. Now, pressured by secular society and from the liberal members within it is repackaging its gay offering but it is still underpinned by a 'love the sinner hate the sin' ethos. The church is making huge media steps and baby equality steps with regards homosexuality. I suspect we will need the old hardliners to die before we see meaningful change but the groundwork is starting.
With regards to shunning it is not too formal (unless you are a vocal apostate) and in many ways the attempt to reclaim 'lost sheep' wouldnt work if shunning was encouraged. In effect some members may unofficially shun and family members are still capable of crazy things so you will always find horror stories.