You wont stop them from entering, but if you give only the doner group the "essentials.build" permission, they will be the only ones able to build or modify the world
Need more info. How many SATA ports do you need, Does your motherboard use 24 pin or does it have +4, Does it use a 4 pin power connector or 8. What slot are you using for the GFX card? PCIE 2.0 x16?
That is probably quite a bit more than I want to get into at the moment lol, Unless you are setting the plugins up and all you want me to do is write a permissions config file.
You cannot make your IP Address static unless you talk to (and usually buy one from) your Internet Provider. You can use DynamicDNS to achieve something like that though.