If your meaning PC, Mac and Android the only computers I know it works on is PC and Mac...not sure about Android. Basically anything computer that can run Java.
No
Yes. Seeds will work on any cracked versions of Minecraft or any versions of launchers. If you would like to try some out, check the link. All those seeds work!
What do you mean? Minecraft saves automatically all the time, so I don't understand how that can be a problem.
Minecraft 1.4.6 mods will work with 1.4.7 sense they are both a 1.4.
If you install a mod it will work in all gamemodes.
By pc I'm assuming you mean Windows. Minecraft works on definitively works on all versions of Windows including and after XP. Minecraft also works on Mac and Linux. Minecraft may work on other operating systems as long as they support Java, OpenGL, and has the capability of handling graphics.
yes but you have to download minecraft if you want it to work
You might have to update your minecraft
then your minecraft is bugged...
no this will only work for one specific update at the time, as minecraft is updated so are the servers with it so if you want to go on newer server then you have to update your client also.
yes minecraft will work and run it might freeze sometimes but it will work :)
it does not work