Google Earth reprentation of Excel data

We have minimal technical knowledge of Google Earth but do have sets of data that which represent geographic "things" - customers, suppliers etc with quantitative and qualitative attributes that we would like to be able to load and view in a geographical context such as Google Earth (other software platforms can be considered if you think better suited to to our needs). This project is to (a) set up some basic working examples that can do simple things such as - plot points, ideally : (i) labelled (ii) in different colours/thickness (iii) with descriptions available - plot straight lines, similarly annoted - plot polygons, similarly annoted Colours/ line thicknesses/descriptions etc would come from our excel data. The data would originate in MS excel. We have grid points for some cases, UK postcodesin others, so ideally we can work with a variety of inputs but can convert ourselves as necessary). We don't especially want to get heaviliy involved in programming - just to edit the data or do minor tweaks to templates like change "red" to "blue" for a line colour etc. The above represents our basic requirement, and we'd be happy if we could do this. Beyond this basic need, we'd like some pointers to anything else we have't asked for but you think could be useful. Our data is mostly marketing related, so we are interested in plotting locations of our distributors, populations, purchasing patterns, sales territories and this kind of thing. Tips as to what kind of free source data exists, like county boundaries, populations and so on helpful (not your fault if there isn't any!). I would hope it can be organised in "layers",so different views/levels of detail and be selected as required.