Healing Done
Healing Done can be defined as impacting any healing that you give out, regardless of whether that's self-healing or healing to other people.
Sources of Healing Done include class passives and Minor/Major Mending. These buffs do impact the tooltip of your healing abilities.
Healing Received
Healing Received impacts any healing that you get from other people, including yourself.
This also impacts self-heals. Sources of Healing Received include class passives and Minor/Major Vitality. These buffs do not impact the tooltip of your healing abilities.
Healing Taken
Healing Taken is functionally identical to Healing Received, just from a different source. Currently, the only source of Healing Taken is from armor set bonuses. Just like Healing Received, it does not impact the tooltip of your healing abilities.
Conclusion
All three are additive within themselves, but multiplicative among themselves.
So Minor and Major Mending are additive for 33 percent Healing Done, but Minor Mending and Minor Vitality are multiplicative for 16.64 percent total (compared to an additive 16 percent).
This functionality only really matters for self-heals, as only Healing Done will impact the healing you give out to others.