Welcome in this forum.
I would like to tell you, as i tell to everyone, if you need something good you need to invest money in it.. Free and good are words that not very often you can meet them together.
About the chronicle decision, its up to you. Eveyone who owns a server, have to be a player before to know how the game rolls.. If you can't decide with chronicle you want as your server just don't open it.
Have in mind that you will need a good budget, if your decision is interlude i would suggest buying an L2OFF extender instead of l2j because l2j is lacking a lot in this chronicle. You can get a dedicated server for ~120$ per month to be able to support 600 players without any problems.
On the other hand, nowadays, DDoS attacks became a trend. Every kid can rent a booter for some bucks and attack your server, I would suggest you to get some good protection against DDoS. This one would cost a lot, starting from ~300Euro. Also you will need some game protections like an Antibot system. Lameguard is one off the best, the cost of it is 200$ if im not wrong..
So a summary in case of my suggestion is:
You need 200$ for an L2Off pack(ONCE), 120$ for your dedicated hosting machine(monthly), ~400$ for ddos protection(monthly), 200$ for game protection(ONCE).
But the most important things are, knowledge and time. It's not hocus pocus, plug&play.
Totally 1000$ for startup, and about 500$ monthly.
Good luck with your choices.