online partnerships quesion

You can have your lawyer create a legal contract for you and get it signed by both parties using the mail. I did it in the past with several people and it worked out quite well.

That sounds good but enforcing it could prove costly if a snap comes up. Maybe having the contract in place helps prevent that.

What you would usually do is pick the country where the company is going to call home. That would then be where the company will hold the primary bank accounts, formal annual/quarterly reporting, etc...

You can have foreign investors in a corporation without any significant problems. If your company is US based, you may have to file additional paperwork, depending on the home country of the other investors.

The company pays all owners/shareholders on whatever basis your Operating Agreement states. The person who lives in a country different from where the company is located will have their own filing and taxes due.

This scenario should be done with a lawyer, as once you move into corporations with owners in multiple countries it can get tricky. One of my last major companies was based in Chicago, and I had one investor who lived in Saudi Arabia and a second who lived in the UK. We had quite a bit of extra paperwork needed that I had never needed before for companies where all owners were US citizens.

While you can draft the Operating Agreement between each other and come to the main terms without the lawyers, I would very highly recommend you have this sort of company formed with proper legal assistance.