Proxies and using with instagram.

Ok so a few questions.

How many accounts per proxy can i run a bot on ?

Im in australia , do i need australian proxies seeings as i will be posting 1 picture a day from here ? or do i try automate that through the bot also ?

What is a good average price for proxies , from aus ?

Any help is greatly appreciated !

Thanks.

Also , is it possible to use free proxies that i've been seeing on the net ?