You will have to share the printer first from control panel->printers and faxes and then install the printer drivers on all the computers you want to share the printer with.

I am not sure but the only reason I can think of is that the ethernet cards have been manually assigned a ip outside the range of the dhcp. If that is true then you may try setting them to autodetect...

I am not a networking wiz, but try manually assigning the ip's to each laptop/desktop within the range of those assigned by the dhcp.

OSI model is representation of networking via seven layers namely.

Physical layer, Data link layer, network layer, transport layer, session layer, presentation layer and finally application layer....

Try setting your ethernet ip to auto assign insted of using a static one.