IMS is IP Multimedia Subsystem. It's an "open industry standard for voice and multimedia communications over packet-based IP networks. It is a core network technology, that can serve as a low-level foundation for technologies like Voice over IP (VoIP), Push-To-Talk (PTT), Push-To-View, Video Calling, and Video Sharing." (From Samsung.) Just restart the phone. If it doesn't stop, have the phone replaced - it's defective.
As for answering calls, look in the app drawer, not in Settings. If Phone isn't in there, that's another reason they have to replace the phone. (If it is, an incoming call should trigger it and present you with at leas the choice of answering or sending the call to voicemail. Just long-press it, then move it and you'll see the home page - drop it, then long-press it again and put it where you want it.)