Paying my brother's fees and gift tax

Hello,

I want to pay my brother's graduate school fees next year. He is my biological brother. We have the same middle name and last name. 

1. Is there any limit of fees I can pay ?

2. Do I have to pay gift tax ?

3. Do I have to report anything to IRS ?

4. If the fees is more than 10K, shall i pay it in one time or in multiple transactions.

I have not paid this big amount to anyone before. If someone can advice whats the best legal way to do this.

 

Thanks