מכשיר הזנה ישיר לבטן בשבת

I'd like to ask a shaalah.

My niece is severely braindamaged, and feeds with a tube through her intestines in her stomache. She is 2.5 years old. My brothers family is not religious, but I will be visiting and want to know whether on Shabbat I will be able to feed her- turn on and off the machine that feeds into her stomache. Am I allowed to charge the machine on shabbos if the battery is dead (I realize that this should be done before Shabbat but in the case that it isn't).

Also, is the machine considered muksah when she is not feeding? If I want to take her for a walk with an eiruv, can I take the machine too, in case I need to feed her later?