Yes I think it is a mistake. おとうとさん means little brother (formal), and おとうさん means father (again formal).
おとうとさん　に　１万円　を　かしました means “I lent 10,000 yen to my little bother.”

Koichi gives you a に you haven’t learnt about yet but the sentence is correct. I think he does it so that when you are going to learn it, you can say “hey that looks like something I’ve seen before” and thus it’ll be easier for you to understand later.
Yes, your assumption is correct. に tells to who the action is done. Actually the syntax doesn’t matter as long as the verb is in the end of the sentence. The particles tells you which words are connected to each other in what way. So
おとうとさん　に　１万円　を　かしました。 could also be １万円　を　おとうとさん　に かしました。 They have the same meaning. Maybe some would find one of them a little odd to say but it isn’t wrong.

ようこそ。
Nice to meet you Dane. I’m Dane too.
Jeg føler mig sej, når jeg bruger tre forskellige sprog lige efter hinanden på den her måde.
日本語の学習、頑張って。

Yes it is just a matter of context. 一人 can mean “one person” and it can mean “alone.”
You can write ん by pressing “n” twice while you are in the Japanese IME.
In some vocabulary the reading for 人 is ひと, for some it is にん, and for some it is じん.

The last sentence could also be translate to “it was not one person” depending on context.

If you aren’t sure which vocabulary would be best to put on the list, you can google both of them and see if one is considerable more common than the other by looking at which gives the most results. For me 聖書 gives 1,310,000 results and バイブル gives 2,740,000 results on google, so I would choose to learn バイブル rather than 聖書.

If it is difficult to look up, you can use wikipedia. E.g. if “The Holy Spirit” was a difficult word to look up you can go to the page on wikipedia about it.
http://en.wikipedia.org/wiki/Holy_Spirit
In the menu to the left you can find the article in other languages. In and click on 日本語 (日本語 means Japanese in Japanese). Then you get to the Japanese article about the holy spirit. There you can see the heading is 聖霊 (which means “The Holy Spirit” in Japanese).

I hope this helped. Good luck.

ようこそ, eller “Rart at møde dig” som vi siger i Danmark.
I’m from Denmark too. I think telling your whole class was the right decision. I followed Koichis suggestion and no one about learning Japanese, absolutely no one. I feel it caused me problems. I don’t know about you but when I find a new interest, and means something to me, I easily get ashamed about it (I think that’s normal). At a point (after studying for a year or so) I began to feel like a weird thing for me to keep secret. You know… it is a little weird to keep learning Japanese a secret, if my secret was an odd sexuality I see a reason not to tell people but learning Japanese isn’t worth being ashamed about, learning Japanese is cool.
When I began thinking about this I decided to tell begin telling people around me. But that was really difficult for me. It was difficult for me because I think it is strange waiting so long to tell people about it.
Today, the most of my friends know it but not my family.
I actually started a thread about it here on TextFugu if you are interested.

http://www.textfugu.com/bb/topic/i-need-some-social-support/

I’m sorry about speaking so much about me but it was just because I didn’t want you to face the problems as me.

Hello Kevin.
To me it sounds fine.