Go to the Cash Shop and press Check Cash. This will refresh any changes you made and should show your new Cash. If this doesn't work, go to the Nexon Website and log a support ticket.
not an error that just means u have max meso
Sometimes if you are logged into your phone, it will stay logged in until you've logged out. You may not be logged into your account on your computer but you may in fact be still logged in on your phone.
Yes, you just look for where you saved it, then click Game Launcher
Yes, you are still logged on in that case. You have to log yourself off in order to maintain privacy.
Yes you can
This is probably because you clicked the Remember Me option when you logged into your account.
Yes
If you still have the installer, run it and install it as you normally would.
Yes
Yes
If you mean MapleStory, there's no such thing. If you mean Club Penguin, Agents are over. There are Elite Penguin Force(EPF), but you still get missions.
Every player is immediately logged out during system updates, so there is possibly no chance of one still being logged onto runescape during system updates.