The Cosmological Argument and the more modified Kalaam version are very similar, with a few semantic differences. I will cover the Cosmological Argument first, and then add a few more things to refute Kalaam.
The Cosmological Argument
The C.A. tends to be argued as follows:
P1. Everything that exists must have a cause.
P2. If you follow the chain of events backwards through time, it cannot go back infinitely, so eventually you arrive at the first cause.
P3. This cause must, itself, be uncaused.
P4. But nothing can exist without a cause, except for God.
C1. Therefore, God exists.
This sort of thing is argued all the time by all sorts of people, often in the form of "Where did that come from?" Theists like to ask this question over and over again. Then, when you say that either nothing came before the Big Bang or that you don't know, they triumphantly grin and act as though they have just proven the existence of God or Allah or Zeus or whoever.
Before I even go any farther, let me point out that this is major argumentum ad ignorancium. The entire family of cosmological arguments essentially say "You don't know exactly how everything came to exist, therefore my god did it." It's ridiculous. To quote a piece of advice I gave to a few other people before, if your "proof for God" works equally well with Chuck Norris, Invisible Sock-Drawer Pixies and Invisible Pink Unicorns, its probably not very convincing to anyone who doesn't already completely agree with you.
B-b-b-breakdown
Now, piece by piece. Premise 1 is invalid because, in fact, not everything that exists has a cause. When you look at a quantum scale, matter actually can pop into existence uncaused. If any of this interests you, shoot me an e-mail and I can give you some great links for this topic, but I don't want to get too far off base in this post. The point is, premise 1 is invalid, thus the whole proof is useless.
Premises 2 and 3 are reasonably valid. Surprising, isn't it?
Can someone say special pleading? Nothing can exist without cause...oh wait except for God. You can't just say that a certain causation rule applies to everything, and then it doesn't. The point is, premise 4 is invalid, thus the whole proof is useless.
Kalaam
The Kalaam argument for God is essentially the same thing, with only a few semantic differences as follows:
P1. Everything that begins to exist has a cause.
P2. The Universe began to exist.
C1. Therefore, the Universe must have a cause, God.
The change to "began to exist" in fact changes little about the overall idea of the "proof."
B-b-b-breakdown
Premise 1 is, like mentioned above, not valid. Not everything that begins to exist has a cause.
Premise 2 is actually correct, though it may at first seem like an assumption. If you're interested in the proof, comment below.
The conclusion is obviously begging the question or special pleading. Even if you were to prove that the Universe had a cause, what justification do you have for identifying it as God? I'll get more into this in a minute.
Meaningless God
Both of these proofs say absolutely nothing. Even if these proofs were valid, what do they say about this "god"? According to this proof, all they have is a god that caused the Big Bang and nothing more. No extras included. This god can't create life, write books, talk to people, etc. In that case, if it was just a cause, why call it God? Why not just call it the first cause? The god that cosmological arguments reference is a nothing god.
Major Assumptions
Stuff exists. It must have come from somewhere. Science can trace it back as far as the Big Bang though there is no certainty about how the Big Bang came about. Prevailing theories suggest that it sprung from the laws of physics inherent in reality, though it is not known. In that theory, the assumption is that the laws of physics are inherent in reality, an assumption that is at least reasonable. Since something, be it physical or more along the laws of physics, had to always exist. To proceed from there, you must make an assumption about what that was. The Big Bang theory assumes laws of physics. To make the assumption that it is God or Cthulhu is entirely unjustified, especially since it would seem even more important to ask the question "Where did God come from?" Basically, you have to assume something. What justification is there for assuming God?
Fallacy of Composition
Finally, this argument employs something called the fallacy of composition. This is when you say "Everything in Set A has properties x, y, and z. Therefore, Set A has properties x, y, and z" or more simply, when you include a set in itself. A practical example of this would be:
"Sodium and Chloride are both dangerous to humans. Therefore any combination of sodium and chloride will be dangerous to humans."
This may sound absolutely idiotic (and it is, don't worry), but people have actually used almost this identical argument to say why amino acids could not have formed on the early earth. They say that they can't form in the presence of oxygen, and oxygen is in water, so therefore the amino acids could not have formed in water as predicted. It seems absurd, but people actually make those arguments. My favorite example of the fallacy of composition, however, is as follows:
"All atoms are invisible to the naked eye. All humans are made of atoms. Therefore all humans are invisible to the naked eye."