Yes, I understood already what all of you had explained.
I thank you all for that...
In relation of the table in my first post... (that time i don't known it better) it seems to me, that optimal (absolutly errorfree) Bandwiths
are simply more ones on 18,432. I thought absolutly errorfree is better than little error included. I like "perfect things" 
The conflics about PWM etc. where an aspect to think about twice,
and I understood that 16 as better usable informatic power is the better way. And Errorfree Bandwidth is not so neccessary as usable
things with arduino.
.......
After all, my Result is to use 20MHZ. Its Power of 2. It's maxmimum speed of my mcu, and is supported by UsbASPLoader, for which i decided to include in my project.
......
Maybe, 16 Mhz is here the better way too, but if I understood right,
clock schould be power of 2. (to get everything work right, but mcu instruction code for 16Mhz which is not sooo neccessary for me as UsbAspLoader supports 20Mhz).
......
Thank you... Greetings
Chriss