buffering work

I have a spreadsheet of sites (lat & long) with a couple of items of data. I want to have these plotted on a map and then be able to choose any of the sites and draw a radius around it that I specify. I want to be able to filter the results of sites that are in the radius by the data items eg sites where data item 1 is greater than n etc. The site locations will not change but more sites may be added to the spreadsheet. The value of the data items will change but the type of data items is a constant