Good luck on your campaign. I would recommend starting with 10 accounts first, getting the hang of things, all the ins and outs first before diving right into 500, or even 100 for that matter.. because it will get overwhelming and you'll have a 90% chance of ending the project, which in essence could be a waste of money and resources. Master 10 accounts, once you have it all down, then move up to 30 or 50 accounts, then 100, then 250.. and so forth. Although the process is being automated, there is still a decent amount of work you'll need to do manually first.. and to do so without prior experience is a recipe for disaster.
I'm saying this off of experience, as I run 600+ at the moment, and even after running 300+ for 4 years.. it still can be a bit frustrating at times. As you build up your network, if you can program I would suggest writing a few custom bots to handle small tasks that you'll need done that aren't included in public bots. 1 proxy per account is my recommendation, some use 2 or 3 per proxy.. but if you're using ipv4 or ipv6, your best bet would be 1 for 1. If it's in budget, invest in residential or mobile proxies.. else there is a good chance you'll encounter action blocks. Run your accounts emulating human behavior as much as possible.. this will help the longevity of your accounts.
There are an array of public automation tools you can use for following/liking/commenting/etc.. depending on what your plans is. Alot of them(gmt2, jarvee, followplanner just to name a couple) offer free trials.. that's a good opportunity to try a few of them out and see which one is suitable for you. The trial periods offered isn't long enough to get all the ropes down though, so I wouldn't suggest jumping into 500 once the trials are over.. slowly build up your network. You can dive right in if youre eager, but I don't recommend it.
There are plenty of journey threads, and other IG related threads here that will answer pretty much any and all questions that you'll have along the way.. try and make use of them instead of opening new threads with the same questions that have been answered already. I don't mind answering questions related to the subject, aslong as they're new questions that haven't been asked.. feel free to tag me in a question if you have a specific question for me, as I'm trying to avoid any PMs related to the subject(as it turns into a flood of questions out of nowhere).
I think that should sum everything up for you bro, good luck on your mission and keep us posted on your progress!