is there any stable version of nginx+apache+direct admin?
Directadmin officially does not support Apache+NGINX, it supports only Apache replacement by NGINX.
So, if to use Apache+NGINX, it does not matter what version of Directadmin you're running. The most stable combination (if it's possible to say so), I'd call Apache
2.2 + NGINX 1.x (The latest stable version is nginx-1.2.7,
www.nginx.org)
is it hard to install and configure all together ?
I'd rather say no, if you know what exactly to do. No longer than 1 hour of work if to do manually and carefully (at least for me). And probably several days on reading docs and forums if you aren't familiar with the subject.
as I understood this solution can decrease the attacks right ?
I'd say that not, it won't decrease the attacks. But it can increase resistance to such attacks, and protect your server from simple HTTP Flood and DoS attacks.
I found this in the start of the guide:
"Warning: The Latest version of CSF does not work properly with DirectAdmin on CentOS 5 machines with Apache 2+"
Wow, it seems I've never seen this warning. Honestly I don't even know what do they base their warning on.
on which version I can use?
I've been using CSF not so long (1 year not more), and since that time I've only one issue with it. But the issue happened on not a Directadmin powered server, which has no apache at all. In my experience it runs well with apache 2.2, apache 2.3 on both CentOS 5 and CentOS 6.
Sorry for my question I am not familiar with this stuff
That's OK.