You might have to update your minecraft
you go on minecraft launcher and go to options and force update you cant update if you got classic
No it will not
You can, it should be in a update soon
Either the server needs to update or you need to update.
You update your minecraft or get the older version. If your minecraft version doesn't match the server's version, then you can't join it no matter what you do.
It usually means the server version is older then your game version. Every time Minecraft updates they usually update the server also.
Nothing you should know its past that update so that will never be answered
The most efficient way t host a minecraft server is ... Sorry but get Windows.
delete a mod maybe and force the update?
There are tons of tutorials out there. If you are running Minecraft Beta 1.8, you should update to the newest version.
Client outdated means that the client (the software used to connect to the server) is out of date. You need to update your version of Minecraft.