Firstly,

I never heard "dir" suffix is used to emphasize the thing that someone is telling about.

As erdinç mentiones, "dir" suffix tells about the scientific facts and used in historical writtings.

Ade1, you mention that you heard "dir" suffix was used during the debate between two Turks when you were in Turkey.
Would it be something as follows,

A= Geçen gün gördüğün araba mavimiydi? = Was the car that you saw a few days ago blue?
B= Evet, maviydi. = Yes it was blue.
A= Emin misin? Are you sure?
B= Evet, eminim. = Yes, I am sure.
A= Yeşildir o mavi değil. Yanliş hatırlıyor olabilirsin. = It would be green not blue. You would be remembering wrongly.

That is another story...

http://www.turkishlanguage.co.uk/adjectives.htm
The above site has some pronunciation examples. The person who created that site would have found a native Turk to pronounce the words. The accent in the pronunciations is so apparent and in some of them he puts the stress on the wrong syllable.

First of all;

Do you want coleslaw with that? = Onun yanında / Onunla lahana salatası ister misin? or Şunun yanında / Şununla lahana salatası ister misin?

-Personal pr. (ben, sen, o, biz, siz ,onlar)

Örnek 1= Senli benli konuşmak / olmak = to talk in a friendly and easy manner; (people) who are on familiar terms.

Bu ne cüret ki benimle böyle senli benli konuşuyorsunuz? You talk in a free-and-easy manner with me, what a temerity is that...This wouldn't be the literal translation but must give you the idea.

Örnek 2 = Sizli bizli konuşmak / olmak = to talk (to someone) in a distant manner. You can not or can only once in a very great while hear this kind of talking in the daily life. You would mostly hear that in the movies or maybe would read in the books.

Artık sizli bizli konuşmayı bıraksak = Let's not talk in a distant manner anymore...This wouldn't be the literal translation but must give you the idea.

I hope this helps a little bit. Someone would go on the answer. Now I can not think of another example. There are some but those do not sound good.

A funny short conversation would be like this;

A= What do you make this soup of? = Bu çorba neli?
B= From everything = Herşeyli.

But B's answer is not good talking. It's imporper. But some like to talk like that.

alabilirim is the correct one.

And also..

1,5 >> This is "bir buçuk" (You can NOT say "bir yarım")
1/2 or 0,5 >> This is "yarım"

For time;

01:30 >> Bir buçuk
04:30 >> Dört buçuk
12:30(p.m.) or 00:30(a.m.) >> yarım ( or on iki buçuk)

plaj : beach, bathing beach

kumsal : sandy beach / shore

There are differences in usage of these words.

For example if I went to a romantic walk on the beach with my girlfriend, I would say

Kız arkadaşımla kumsalda yürüyüş yaptım. NOT Kız arkadaşımla plajda yürüyüş yaptım.

Plaj is mostly used to describe the shore where everybody who wants to swim gather and set up their beach umbrellas and spread their towels on the sand and lie there. It's a crowded place and kids dig holes on the sand, there is always an action and movement.

But kumsal is the general name of the sandy area near the sea.

I hope this makes sense

No difference. But "dil" has some connotations. Other than it means "language" it also means "tangue, promontory, point, spit, bolt, index etc...