@able to ask,
1) Should people be disgraced for not agreeing with homosexuality? i.e. Should those with the opinion it is acceptable be treated differently to those who believe it is wrong?
First, disagreeing with homosexuality is like disagreeing with blue eyes or red hair. You might disagree with allowing same gender marriage or allowing homosexuals in the military but homosexuality exists and is part of the human makeup. Disagreeing with someone's private consensual sexual practices seems silly. It might not be for you, but it's really not your concern either. Imagine how people would look at you if you went around saying you disapprove of people being left handed. I think the response would be 1) that's silly and 2) why do you care?
You ask should those of different opinions be treated differently. If that opinion results in active discrimination, then yes. No one should be denied a job because they hold a questionable belief as long as it doesn't impact their job performance but if those beliefs prevent appropriate performance of their job, that situation needs to be addressed. This is not just restricted to gay rights. If someone has a problem with other religions, with other nationalities, etc you have the same issue. When I was in the military the rule was to stay away from sex, politics and religion in the workplace and you would be fine.
There is a special caveat here for people with extreme amounts of authority and power. Politicians and business leaders typically fall under this situation. Because of the power they wield if they are seen to hold prejudicies that people feel will cause them to do their jobs unfairly, there will usually be a backlash even if there is no evidence that they are not acting in a fair manner. The Mozilla CEO (who donated thousands of dollars to prevent homosexual marriage in California
) is one example and it is an interesting one. He was not forced out by activists or the governement, he was basically forced out by his own employees who felt he did not represent them, that his views would taint Mozilla and compromise its ability to succeed. The recent case of a basketball team owner who made racist comments
is another example. I don't know that you could say how his beliefs have negatively impacted the Clippers but now that they are widely known, they clearly taint the entire organization. Note that the backlash can go both ways. Replacements Limited took a strong stand against a gay marriage ban and was pummelled by the public
2) Does claiming that homosexuality is wrong constitute discrimination against homosexuals? i.e. Is it the equivalent of discriminating against a group of a certain race, age or gender?
Maybe and Yes. Clearly when the President of Russia says homosexuality is wrong, people feel empowered to beat them in the streets. It's not hard to see the correlation between authority figures who publicly speak out against homosexuals (or minorities) and violence against them. They are entitled to their opinions, but their opinions also tacitly condone discrimination by the wider population. As for an individual, claiming homosexuality is wrong doesn't on it's face constitute discrimination but certainly leads people to wonder and business owners using that position to deny services to people they would otherwise do business with is clear discrimination. Is it equivalent to other forms of discrimination? Of course.
3) Should the religious and racial hatred act in the UK be extended to protect those for hatred against their sexuality?
Not being from the UK I really can't answer that but if a law prevents discrimination against religion or race, I can't see why sexual preference is any different. Those who would claim otherwise see sexual preference as a choice, something that has been repeatedly refuted. You can choose to refuse service to someone who does not meet your dress code. They can always choose to dress appropriately. Sexual orientation is not something someone can don or doff like a sports coat.