Hey I knew this. Once I entered the chat room and thehandsom said "Abla geldiler".

That´s interesting. Like a more formal way to talk about a third person. Thanks, gokuyum.

treat someone well/bad/right/like dirt/with justice/equally...

Thanks, huko, I was careless.

Do you use this dictionary:

http://tureng.com/search/business%20intelligence

If you don´t you should. It takes whole phrases and provides a good amount of professional terms also.

Kendisi iyi bir yüzücüdür, ayrıca güzel de tenis oynar.

In the above sentence kendisi is used almost like the personal pronoun o. I don´t know the context, though. What kind of a situation could motivate this choice? Is the speaker comparing this person to others, connecting the sentence to what has been said before or just stressing the third person actor here?

My Try:

Hafif ilişkilerin ilerdeki mutluluğunu mahvetmeye izin verme.

Interesting. And then again, if var roots from a verb why does yok look so different?

No it is a quite usual form. It often tranlates to English with past perfect / pluperfect but often only with simple past tense. tunci writes about it beautifully here: the speaker is narrating a past action which he had witnessed.

               http://www.turkishclass.com/forumTitle_55447, post 10

Btw, I think this usage is the reason why Turks often overdo past perfect when they speak English  -  if you have noticed.

sunsun ´let him present´

sünsün ´let it stretch´