He's a friend.
Working on it for the past year.
It is for a charitable organization.
Ask him, how you can compensate him.
He probably has his own rates.
But since you are his friend and this is for a charity, he may or may not accept any money.
Up to him.
Just ask him.
But 1 year working on it off and on, is a lot of time.
Website Developers, do a lot.
It is not a template.
For having an artist or logo... he will then have to integrate that into the website, too.
Ask this person, how much?
And check online for what is the going rates in your area.
Or, your friend, may know of someone who can do that.
Tech people are very networked into this realm and often know people who do graphics for websites.