So does this mean i have to do all of these 3 tests before i ever acutally get to fly? And after those 3 start i could then start working on whatever hours I need for the practical part, being around 60-70 hours?
No. You have to have the solo written test done before you can fly solo. This usually happens after around 10-20 hours of flying experience (10 is the minimum allowed). You need to have the official written test done before you are eligible to do the final test (known as the checkride). The checkride itself also contains a theory component (oral, not written).
These are the only constraints. You can do as much flying as you like before you solo, but you can't solo until you have done the pre solo written test (there are other requirements before you can solo too, this is just to address your questions about how theory and practical training are mixed). Similarly, you can do as much flying as you want before the official written test, but you won't be allowed to the checkride until you have done that written test. You could also do the written test before anything else if you want.
And when do i need to have the medical test done and when the student pilot license?
You need both of those before you can fly solo. But there are no training requirements to get them.
Think about it like this: to get the license, there are just 2 main requirements - pass the official written test, and pass the checkride.
For passing the written test, there are no special entry requirements as far as I know. You just have to have the knowledge. Some people pass the written before they start any flying at all!
So, on to the other major requirement - the checkride. To do that, first you have to have a minimum of 40 hours, which must include at least 10 hours of solo flight. There are other requirements on what the 40 hours must contain, such as a certain amount of night time flying etc., but you don't need to know about that in advance.
Before you can do those 10 hours of solo, you'll need to:
* get a medical
* get a student pilot certificate
* get enough training to convince your instructor that you're safe to fly solo
* pass a pre-solo written exam administered by your flight school
I hope that breaks it down a bit more clearly.