Recommended Hosting? Choose either http://www.trinitynetworks.netor https://wanhosting.net or http://www.phytonhost.biz
Magandang Anti-cheat? Harmony but you can also choose HaShield and such check m ung paid section ntn dto sa forums
Around how much ang pag-run ng server? Depende pero most probably around 400 to 2k per month if kakasimula plang depende yan kung mayaman ka HAHA
About sa pag-gawa ng server, here are some guides:
Server Side Setup Guide(For Installing in Windows - Usually for Test Servers): http://rathena.org/board/topic/53291-guidehow-to-setup-a-ragnarok-onlineserver-side-only/
Server Side Setup Guide(For linux - This is commonly used OS in VPS Host): http://rathena.org/board/topic/53369-how-to-setup-your-ragnarok-server-in-linux/
Adding Custom Items Guide: http://rathena.org/board/topic/70005-guide-adding-custom-item-renewal/
Downloading the newest trunk here in rAthena you'll need these:
http://rathena.org/board/topic/56594-guide-svn-checkout-using-tortoise-svn/
If you're using 2012Clients adding custom items you will use lub not lua, so here:
http://rathena.org/board/topic/53344-compile-other-way-lua-to-lub-files/
If you want to add custom maps in your server:
http://rathena.org/board/topic/53375-how-to-add-maps-in-my-server-linux/
If you want some basic scr modifications to be done:
http://rathena.org/board/topic/53426-guide-modification-faq/
Well if you don't know how to recompile or compile your svn:
http://rathena.org/board/topic/53726-compiling-your-server-in-linux-os/