How can i change the random number generation in the code , i want to move step by step +1 from a certain base point not +random number , is it something easy to do?!
May I ask why you'd want this? You're basically taking out the randomness, making it less secure.
I do the opposite: add an extra random-file, just in case the standard random isn't random enough.
-s <file> Seed random number generator from <file>
1) Why there is no difference? If you start every hour from some random seed, there is probability that you could start from the same wrong seed which you already checked earlier.
Vanitygen uses a different random each time you start it. Chances of using the same seed are small enough to neglect.
2) Why there is no "maximum"? What is "difficulty" mean then?
Imagine throwing a dice: you want to roll a 6. With 6 possible outcomes, I'd say the difficulty is 6. The more times you try, the more likely it becomes to roll a 6.
But, there is no "maximum" number of tries after you're 100% sure you've hit a 6.
Vanitygen has the same probability as this analogy.
So, my statement is:
Maximum Time for prefix finding (with guaranteed result) = Difficulty Speed
For example, with speed 1000000 keys/second I'll find prefix with 264104224 difficulty with 100% probability for maximum of 264104224/1000000=264 seconds
You're wrong here. Suppose you're really unlucky, and rolled your dice 263 times. The next roll still has a 1 in 6 chance of being a six, there is no guarantee.