Need some help for secure server

[Luny]

Hello, i have some questions.

I'm going open a ragnarok server but they are hackers who already told me they are going to hack my server....

I need some help for the vps and preventing ddos and sql injection.

First is my choice on the VPS:

VULTR BUILD:

Actually i took a vultr server at 40 $ months with windows server 2012. The DDoS protection cost +10$

80 GB SSD $20/mo $0.03/h  2 CPU 4096MB Memory 3000GB Bandwidth

This is the actual config that i have.

 

OVH BUILD: 

I want to know if taking : OVH  with this config is actually better ? cost 28 $/ months but without ssd , and less GB, apparently the protection is already in the 28$

RAM 4 GB

Cores 2

Disk 50 GB

 

My server is going to have ~ 300 people connected on. Is the SSD is a must have ? Does the ddos protection that ovh provides is going to help me to secure my server ?

I want know more about security, what can i do for protecting my server from DDOS and SQL ? 

I'll buy and use gepard shield, before opening the server. But i think i'll need some more secure, do you have any tips ? i'm on a windows 2012 server , any advices and suggestions will be greatly appreciate.

I'm clearly not a pro about security.

And my last question :

On the client folder i actually have in the clientxml, is it safe to give that to players ? 

<address>my ip serv</address>
        <port>my port </port>

 

About the sql database, i don't know how to protect it, i only used MD5 password actually

Thank you for reading, hope you can help me !