As your children learn about playing on MCSG, they will come across many different types of people.
There are hackers, who will do whatever they can to ruin everyone's day - Many people have lost many games because of them. Your daughter will no doubt encounter them if she plays on MCSG.
There are competitive MCSG'ers, people who have hundreds (A few have thousands of wins), and they can often chance across your daughter, and possibly K.O. her. She must be prepared to kill and be killed (In-game, of course.)
There are other newbs, who will often have massive teams. She may be invited to such teams, or form her own if she wishes. How she handles this is her own choice, but communication will be important - typing, for the most part.
She may be asked to Skype Team. This is a very common occurrence, and nothing to be shocked at. Some people at the age of 10, or even 9, are starting to Skype Team. I, for one, have members in my clan that are or were as young as 11 years old when they first started Skype Teaming. It's entirely up to you and your daughter to decide whether or not she is allowed to voice-team.
And, of course, there are Staff Members. They will be polite, they should handle any issues in-game or on the Forums, and they can be relied upon if someone is troubling your daughter - Assuming there is one in-game or that she can talk to. They are surprisingly rare in-game. In fact, unless you know one or someone called a Moderator because they suspect someone of hacking, you can hardly see any. That is, in the higher-numbered servers. There are something often referred to as "Lower number servers" where it is harder to log into, but you can see staff there more often.
I'm guessing you can infer at the other types of people.
One thing that can be almost guaranteed: Her typing will improve.
As she meets new people, she will have to learn to type with efficiency. Hopefully, she will learn to distinguish from a "newb" style of typing and an experienced typer. And, maybe she'll choose to learn to type properly! Because communication is a major part of teaming, she will have to learn to type faster - And in a fun environment!
I, for one, learned how to type this entire message above ^^^ in 5 minutes, even while in an MCSG game. That goes to show how fast you can get by practicing typing correctly, quickly. Using a typing tutor program just isn't the same.