Hello John!
About building your website. Unless you know advanced website programing the best option would be to find someone who knows the advanced web coding needed for your website. Maybe you could use people in the Philippians to do the website at a fraction of the cost; then just pay them with paypal. Although that would might be too technical for someone starting out. I have never heard of any web host service that build auction websites.
As for taxes; be a good boy and pay your taxes haha but seriously don't stress who you need to pay taxes to yet. You need to first be making money in order to pay the taxes on it. If its really bothering you, i would talk with an attorney
I have used paypal when i was under 18. I actually used years before then.
Hope this helps ya!

John