My 8 year old son has been invited to a birthday party for a friend. What is the appropriate amount of money to spend on a gift for a child of this age?

I'd say this is more a question for his peer's parents than Quora. Different communities, cultures and socio economic groups will all give different answers but only the people round you, know what's the norm there. Maybe casually ask one of the other kid's parents if they've got any ideas for a present as you don't know what the kid likes and that might give you a clue. Mind you, bottom line, the appropriate amount to spend is the amount you can afford.

Was anyone in the Bible a homosexual or lesbian? If so, who?

There is an interpretation that the relationship between David and Jonathan was homoerotic. Samuel 20:41 describes when David and Jonathon part company as the former has to escape from the court of King Saul, who is intent on killing him.The text leads with

Can a woman get pregnant after menopause?

Absolutely! And a good reason we have so many mom's with"surprise" late life babies :) Women assume that because they are not having periods anymore they can't get pregnant. Not so, you can still be ovulating even if you've stopped having periods. So the only way to know safely

Assuming homosexuality is natural, what is its 'purpose' in nature?

As far as I'm aware it doesn't have a ‘purpose' in nature. You are attracted to whom you are attracted to because they would make good mates given the standards your body is using to determine potential relationships. That you pick someone that you cannot have children with isn't unique