Does anybody knows is Mozilla in combinations with residental proxy enough for FB account farming? Do I need Multilogin app, or not ?
yes you need MLA or nested VM's for best footprint diversification
Thanks for the answer. But do I need proxy together with that MLA? If yes, could you recommend me someone?
you always need a proxy, and i can't recommend anyone sadly - but if u do a google search for private exclusive proxies then u should get some options
1. It should be "Private exclusive proxies" ? I have residental proxy, thats not good or .. ?
2. What about 3g ?
3. What about data centar?
Attila already covered the UA/Footprint topic so I'll chime in on the proxy front.
You definitely want to use ONLY Residential IPs and never access those farmed accounts from datacenter IPs(aka most proxy services out there)
Here's a list of 3/4G/Broadband Residential Proxy Services:
1)Oxylabs
2)Luminati
3)Affiliatestealth
Its best if you access your IPs from a mix of both cellular and broadband IPs and instead of only 4G or only broadband ones, since real accounts aren't only used on a LTE connection nor only on a broadband one 
But I can use also my 3g network I have on my mobile phone right? Just each time I log in I will need to restart and make new IP, right?
Just make sure you are not logged in to one of your facebook accounts on the app or any of the browsers installed. It might be better to delete the app altogether.
Why is not good to leave it logged in on Multilogin app ? I am constantly logged in into each Facebook profile in each Multilogin profile and there was no problem from that side?
What do you mean by nested VM's? What is the difference between a normal VM?
If you use multi-login app and make sure you keep the same IP as long as possible you will be good. Changing IP's within the same city once in a while will be fine.