How can I accept money in US if I am based outside?

So I have this website which is actually attracting a fair amount of traffic. Based on customer interest, I can turn it into a $2000 a month side project. But I am based in India, and don't have any experience with payment gateways.

1. How can I accept money in the US? My customers are mostly teachers in US. Any gateways I should look into?

2. Can I use Paypal?

3. How can I take payments of a dollar each from each customer? What would be the cheapest service that can help with this? (Due to minimum payment in payment gateways)

Please let me know anything I should know. Thanks!