Okay, here we gooo
Raise Spectre has a base of two spectres max at level 11, three at 21, and four at 31.
Carrion Golem's Leap Slam has a 4 second cooldown, and doesn't repeat with Multistrike unlike some Spectre leap slams. It deals 180% of their base damage. The Bone Cascade has a 4 second cooldown, can multistrike, has 10% less attack speed and deals 65% of base damage, but can hit enemies multiple times with each cascade. The non-cooldown attack deals 135% of their base damage with the first two swings which are wide cones, while the third to sixth swing deals 162% of base damage with 200% more attack speed, but in a smaller rectangle (For bursting down enemies that survive the first two swings). At level 20 of the gem, they do an average of 372 damage per hit, with an attack time of 0.9 seconds. They have 1067 accuracy rating at gem level 20, the same as other minions.
The Delve chest mod can still give +1 to maximum spectres, as do Midnight Bargain and Queen's Escape and Decree.
Feeding Frenzy's reminder text: (Feeding Frenzy grants 10% more Minion Damage, 15% increased Minion Movement Speed and 15% increased Minion Attack and Cast Speed)
Edit: Updated the Carrion Golem hit damage, as I mathed wrong.
Editedit: I've gotta head off now, but I'll catch y'all tomorrow if there is spare time to answer some more questions!