Hi coykiesaol, Heathers fall basically into 2 groups, there are the summer flowering and the winter flowering ! As a rough guide for soil, summer flowering varieties need an ericacous soil but winter flowering varieties will grow well in both acid and alkaline soil ?
Both types will respond well from having compost or even peat added when planted, it will help establish them much better ! I would also mulch with peat, this will not only help the heathers grow better and encourage them to root into the mulch as they grow but it will look much nicer and inhibit weeds growing from your 'grey top soil'.
Now this is the most important bit, ANY heather will look alot better if trimmed after flowering, remove the flower stems to encourage a nice compact habit and personally I think it will look alot nicer if you plant in groups of the same variety, rather than too many single plants which to me looks 'bitty'
In planters, I'd be inclined to use some foliage shrubs as well, to give a bit more interest, something like variegated dwarf Pieris, or Euonymous 'Emerald and Gold' or E. Gaiety or even some very slow growing conifers !
Lannerman