I've hired a butler, but he's disappeared and when I call him to come over..

Keep trying to call him, or locate him on the map or invite him to aparty and when you get the chance, fire him . Hope this helps )

My butler is standing outside and she won't come in but I have a bed for her

I'm having similar problems, all I can advise is ways to delete, or reset the sim so that they are not working for you anymore. I cannot figure out how to get them in the house as of yet.

1)to restart the sim

Hold Ctrl+Shift+C;
Type in resetSim Firstname Lastname; (If the butler's name is Butler McButler, it would go resetSim Butler McButler)
Press Enter.

2)to delete the sim

Find the butler;
Open the console with ctrl+shift+C again;
Type in testingcheatsenabled true ;
Press Enter;
Hold Shift and left-click the butler;
Click "Object.." and then "Delete".

When the butler takes out the weekly salary and the window pops up to tell you, don't hit the "x" to clear it, instead click on the picture of the butler in the notification. It will take you to their location. The only way to get rid of your butler without cheats is to fire them in person...