WTF Reanimation??

This technique is insane it brings back people from the dead i get that and im ok with that but how do they have chakra dont you have to be alive for that. I mean if their using the hosts chakra than wouldnt the host have to know fire style for example for the ninja to use scorch style. And how if thats the case is their chakra infinite shouldnt it be done when the hosts is. How if theyre being controlled does kabuto for example know the handseals to use zabuzas water dragon jutsu he never seen him use that technique.

mehh.. too flipping weird. insane people are always insane