The pansies should be fine with the heathers. I wouldn't try Hellebores with heathers, as Hellebores like lime. They'll do fine for a year or 2, then they'll get a black fungus. Add lime, they'll recover . . . but then, of course, the heathers will be unhappy!
Small bulbs--crocus, small-type daffodils, Muscari, snowdrops--should be fine. You could try a small Azalea, such as Hino Crimson, in the container, or a very dwarf Japanese maple. Hardy Geraniums will also do well . . . there's a lovely one named "Midnight Reiter", with deeply cut purple foliage. Also Heucheras--they come in all manner of foliage, from dark purple ("Stormy Seas") to chartreuse ("Key Lime Pie"), to bronze ("Peach Flambe"), to silver and green ("Snow Angel"), to my favorite: purple with pink mottling "Midnight Rose".
(edited to fix typos)