League of Legends is a MOBA, Multiplayer Online Battle Arena. You battle with your team to fight the enemy team to destroy towers guarding the enemy base, and then destroy said base. An average match of League of Legends lasts for about 20-50 minutes, though some matches may exceed this.
In the new playstyle, Dominion, your team tries to capture a majority of the 5 capture points on the map while defending the points you own. The team who can keep a majority of the points longest wins. These matches usually don't last more than 25 minutes.
There are (currently) 95 champions that any person can play, after unlocking them with real money or in-game points, each with several abilities and all with their own stats. By working with your team you can choose a character to support others, kill the enemy team, distract the enemy team or keep the enemy from acting.
The most important thing here would be the server you're going to play on. You both have to play on the same server (region) to be able to play with or against each other. For example, you both have to play on the Vietnam (or Singapore) server.
It's important to note that, due to the way the internet "works" in that region of the world (and due to different contracts), you both might be forced to play on different regions based on your IP (as you already mentioned from your previous experience). The only way around this might be using VPN software, but this might cause additional trouble (additional lag, being suspicious, etc.).
Overall, it's really hard to estimate this, you'll probably have to use trial & error for this (even with IP restrictions you might not necessarily be restricted based on your actual IP sub net for example).
Best Answer
The files are only pinging as bad on one or two anti-virus programs and not on any of the more reputable ones. Anti-virus software isn't perfect and false positives happen.
It is far more likely that one anti-virus program is wrong about it being a virus than it is that almost all of them are. The files are probably safe.