First question:
I use simple queues to slow down p2p traffic and to limit bandwidth for each customer..
For the following example I have a problem..
Internet connection with 10 Mbit
For all customers a queue with max 1Mbit download and one queue for P2P-Traffic with max 2Mbit download.
I want that each customer has a max download of 1mbit, but with the configuration above when only one customer is online he can use the full 2mbit with P2P + 1mbit for other traffic so he can use 3mbit, but thats not what I want!
How to do that all can use max 2mbit P2P and each customer only have 1mbit download?!?
Second question:
I think burst in queues a usually used for short time. But I try to limit customers which have a high amount of traffic over a longer time.
Over short time it works fine. An example how I calculate the settings.
I want that the first 5MB go fast with 1Mbit an then slow down to 128kbit with a Burst Time of 100s.
Max Limit: 128k
Burst Limit: 1000k
Burst Threshold: 410k
Burst Time: 100s
The only thing that was to calculate is the Burst Threshold.
5Mbyte * 1024 = 5120Kbyte 5120Kbyte / 100s = 51,2 Kbyte/s (the threshold is the average over the burst time)
51,2 Kbyte/s * 8 = 409,6Kbit/s (1byte = 8bit, bandwidth is in kbits)
When I use these Settings in experiments it works really exactly. Till 5MB 1 Mbit download an then slow down to 128kbit !!
Now the question. I want to use it for much longer time. Maybe I want that a customer can max download 1GB on one day with 1Mbit an then slow down to 128kbit.
When I calculate the settings for the queues like above it doesn’t work. The example with 1GB on one day i tested till 2GB an there was no slow down! 
Is there a max Burst Time so that higher values doesn’t work? In documentation I read that it is an Integer value so the limit may about 32786?