As far as the impact of a shopping center on value, you will have to get someone to do a long-term analysis of similar situations at another, established mall. Cherry Hill might be a good one, since it has residential nearby. Any other comment will be a guess.
Please think the economics through. Bidders on the property in question will determine the market value, not any other figuring. If the property is listed with a Realtor, ALL the interested prospects will be publicly informed. Do you think that they will all step back and let you have the property for less than market value?