Is it safe to install Launchers for Android which require quite a few permissions?
Those permissions (call, SMS) are in most cases used for "quick-access-widgets/shortcuts" the launcher provides. To create a call widget for a contact, the contacts need to be read, which again might need the account data in some cases to retrieve them.

So all those permissions are obviously making sense in context of a launcher. Of course this does not mean they cannot be abused. So I'd either stick with a heavily used / well known app, or have additional protection (PDroid, LBE).

You explicitly mentioned Apex, which I use on some of my devices. On others I use GoLauncher EX. I also use LBE to keep watch. None of these two launchers ever misused these permissions (at least I never got a warning) -- though I must admit I did not check all the logs thoroughly all the time.