Research indicates that the bulbs planted without bonemeal do just as well as bulbs planted with it.
Buy the younger plant. The younger plant develops a deeper, more widespread root system. Avoid creating too plush an environment for the new plant or the roots will simply curl around in the new hole and avoid sending roots out into the native soil. Removing competing weeds encourages the plant to grow. Avoid compacting the soil around new plants and old plants, too, for that matter.