For an ip or device that is in the local network, it's a very straight forward cache table lookup for its mac address. how does arp work for an ip or a device which is in a remote network?

It doesn't really. The address is recognized as off the local network, so at the IP layer the packet is sent to the router, whose address is in the ARP table. As the packet travels to different hops, the MAC address is updated to the next hop.

Is this a statement or question?

Aconsequence when using open source software is c. no support