I just realized I forgot to tackle Deepened Pact in my OP. Thanks for that.
After having a quick read, I thought that, it would be better if Deepened Tome Pact had this function instead: Chose 3 warlock spells of your choice. You can cast those without expanding a spell slot.
I'd argue this would be better because Warlock has a lot of decent spells where the level of the spell slot doesn't matter such as Hex, Expeditious Retreat, Misty Step, Mirror Image, Hypnotic Pattern and Fear.
