Zippi,
I have been abuyer, and still am sort of,
Negotiating: I would use your shop experience, about negotiating prices from suppliers down, and maybe with your experience of dealing with bulders and workmen, and negotiating prices. Do they have some specific questions on negotiating?
Influencing/persuading - would talk about finding out what the other party is like, what pushes their buttons etc: i.e potential results, facts and figures, 'expert opinions' etc, and constructing your arguement in the relevant way to that individual.
Key Pefromance Measures - is this wrt to suppliers, or your area's performance?
iF SUPPLIERS, IT WOULD BE ABOUT MEETING CRITICAL DATES, SERICE LEVELS (DELIVering stock when you need it, on time),qulity standards, meeting delivery requirements (i.e complying with company supplier manual if applicable)Using/complying with sytems required by the business, i'e EDI ordering etc.
If for your area, it weould be sales budget, profit/margin target, cost controls, stock levels, stock avalable on time for re-ranging in store etc.
HTH