The most listed brands in Laptop Motherboards are HP, Dell, Supermicro, Kingston, Juniper and Nortel. Every listing names its manufacturer and part number, so you can search by either.
Both. Of the 180 listings, 117 state a condition: 117 are refurbished. The other 63 do not record one, so ask for it when you request a quote. The condition shown on a listing is the condition you receive.
8 Laptop Motherboards listings show a price you can order at. Items marked "Call for Price" have a Request for Quote button; send the part number and quantity and the sales team replies weekdays between 8:00 am and 5:00 pm PST.