lock proxy by domain / checking proxy by url / browser emulating

[vortex14]

When we do too much requests through one proxy we get block from the server.
When we create 100 threads for one domain and we have only 1000 proxies and each request will finish for 2 seconds for one thread. What will happen? Will be proxy rotates around circle or not? Without lock or not? Will be lock one proxy by locktime for each domain ?
As example I have 2 domains and 10 proxies. I want to use 1 proxy not more then 1 time per 45 seconds / per domain. How can I set this parameter ?
How can I set url for checking proxy for each domain which I scrape? Sometimes server blocks very fast proxy because request was send without browser emulation. I need to change basic url to emulator url for correctly checking proxy.

What do you think about it ?