Hi pal,
1. I am not user what kind of LNK user you are, but it's NOT possible to send 5000 contact requests adn get accepted in 5h, nor 5 days or 50. LNK has a strong acceptance policy. It all depends about acceptance rate. So if you send first day around 100 invites and get ar. 50 acceptance, than u can keep this way, otherwise, send less and so on to avoid getting banned or worst: canceling your profile for abuse. It's not as easy as looks. This results 2 - it only depend of how strong your profile is/rate of acceptance. For 5000 it will be in around 150 days for an average profile. Maybe less for a person that has some influence, and much more for an simple employee.
Cheers,
Andrei