3 times,
You can add multiple blocks to the Voxel List by just using /vl # multiple times with different IDs. To clear the Voxel List use /vl clear.
Yes, by default the world will save when the server stops. I have found even when the server crashes, it will still save the world. Any issue involving the Minecraft server saving is 9 times out of 10 probably not the server, rather something else (i.e. griefing - or when a user destroys creations by another user).
It varies. I, for example, got my Minecraft account premium in a matter of seconds, but in times of high server load or just bad luck the process may take hours or days.
Im not sure this is correct dude but ive heard that you must keep your computer running at all times you want the server to be up.and have the program open and running. i think that's all you need to do but if im wrong sorry.
No unless you have an corrupted file
It depends on what multiplayer plug-ins you have for administrative things. You might need to op him "/op [user]" If that's not the case, make sure he doesn't have a bad login. A bad login is when you leave and join a server, or get kicked from a server multiple times/banned. This could be the result of him not being able to talk. - youtube.com/user/DjOver9000 message me for feedback
Once.
Nothing will happen if you keep installing and uninstalling Minecraft. Minecraft does not track how many times you have installed it nor does track how many computers you have it installed on. The only drawback is if you uninstall Minecraft by deleting the .minecraft folder you will lose all of your saved worlds on that computer.
minecraft
hit a two times
Some times.
You can apply to become a reporter for The Times newspaper as many times as you want. You will probably get blacklisted if you apply more than a reasonable amount of times and the answer to your application isn't going to change.