I'm all for people setting up little networks to play around with each other on.

But in your case, you have to worry about:
1) did he give you a real address
2) was it really his address, or is it a trap?
3) what are the policies of the networks involved.

As for your questions, a lot of books talk about how to do that.

I agree with chrisj on this one

I suppose it goes down to how well you know the other person, but to be on topic it is all completely possible

Think about the possible laws in the US and Russia though, they have been quite stern recently with China recently with attacks

It's quite easy:

PS: Hacking is not limited to a network.

References:
http://9gag.com/gag/129192/

Sorry guys, I just had one of those days 

Lets assume all this is on the up and up.

If you search around the forums for books, you'll find the lists we've all made.

Look up the different frameworks for hacking. There are steps.

Step 1, step 2, step 3, etc.

usually the first step is enumeration.

But if you really want more hand holding, look on amazon for books with Hacking in the title. Or F0rb1dd3n.

*Edit:
I'm all for teaching people, I'm all for spreading knowledge. I'm not about helping people get busted for being stupid.

Mannol: you have to understand, when you get into computer security / pen-testing you will develop a sense of paranoia.  Someone showing up the first time asking how to I hack this without giving us detail, is going to get us to be leery. We're worried about being targeted by corrupt people.

Also a lot of what you're probably wondering has been covered in this forum in multiple places. a little bit of searching will do wonders for you. Look around some more. Learn to search, not just the search bar up top but with google. Being able to research is key to the first step in doing "hacking".

if you want to learn, and build up skill, build a lab. you can do it fairly cheap and easy, and there are lots of discussions on that in the forum.

If you want to really have fun, and test your skill. You and your buddy can set up labs, and then set up a vpn connection between them. Then have fun trying to hack each other.

remember being ethical doesn't just mean you have permission to do the hacking. You have permission from the proper person to do the hacking.

One more thing to remember. Verbal permission is worthless. Must be written, and dated.

Originally you lived in Russia, and your friend in USA? Now you live in Bosnia? Smells like you're not telling the truth, misterrr Mannol

PS: If your packets do go through another country, there may be laws in that country, that applies to your packets. Hence the reason you could worry about the law, if your actions are unethical and against the law in the countries your packets travel through.

Having an IP-address alone, is hardly enough for any attack if he's behind a router with NAT enabled, and all ports on the external NIC / interface are closed.

As many others have already recommended, why don't you search around these forums a bit? And other forums as well? There's like 1000 hacker forums or more in this world, and plenty of sites too. 

It's static IP. And thanks for your advice ill do that!