Djape,
thanks for so long reply, really appreciated here! 
The trouble is, that I read the manual, several times
It is like when you read book about programming, you “understand” even higher concepts, but then you sit in front of empty source code editor, and you are kind of struggling writing simple “Hello world!” app 
Of course I do understand what you wrote here, it is just that I don’t understand what is the correct model to seel the bandwidth. Here in CZ, we can buy ADSL (end users), of eg. above mentioned 256/128, with let’s say noted aggregation of 1:20, which means, that you are sharing the line with 20 users at Telecom or something like that? The thing is, that your line runs decently fast all the time.
Whereas when we sell our 256/128 and put even 8 users ther to share it, the users are struggling for bandwidth as you noted. Setting queue for each particular user, I would have to higher the price no? I have 1mbit, 8 users, if I set 1 128/256 to each user, actually how my line is divided? The thing is they are buying very cheap aggregated lines from us, not guaranteed ones, for which I would raise the price of course. So maybe the solution will be to limit those downloaders somehow, or provide some throughput to P2P apps, or just limit P2P to last evening hours …
Also - why, in my case, users would not have QoS? What I am confused about is, that there is several alghoritms (bfifo, pfifo, sfq, red, pcq, htb), some of them being shapers, some of them prioritizing only, and then we have simple queues and queue trees, and I am not able to find out, what to start-up with, and to which design I should stick. Different ppl use different methods, but there must be “the one” 
OK, thanks a lot,
I will not reread some docs once again,
-pekr-