Hi Treantmonk - your guide has been invaluable. Thank you very much for your contribution!
One quick question - does being able to cast (xg) Dragon's Breath on your own familiar - obtained with Find Familiar improve the rating of the spell in your opinion?
Note - you can actually cast Dragon's Breath on the familiar anytime its within 100 ft - since it can deliver touch range spells for you, using its reaction.
The way I see it the familiar's actions in combat are more or less useless - while giving it the ability to do 3d6 dmg per round in a highly mobile (e.g. with a flying familiar) 15 ft cone seems effective. Note, since it is a bonus action to cast, you can still get in some cantrip damage the turn you cast it, as well as the 3d6 from your familiar.
Especially against creatures without ranged weapons, or hordes of weaker monsters it seems devastating. Also, I can think of scenarios where sending in your familiar to start fires all around an enemy encampment might be fun & highly effective.
Note, per
https://www.sageadvice.eu/2018/02/07/can-you-cast-dragon-breath-on-your-familiar/ - this use is legal - since using the ability Dragon's Breath grants is not considered an attack, but an ability.