Pricing question and mission completion question

First off, I would like to know the value of some of the monsters in my collection. The list is as follows:
Rank A/A+
Fafnir+ lvl1 [Critical Rate Up (1)]
Black Gear Wraith + lvl9 [Impulse Down(1)]
Tiamut lvl20 [Decrease Enemy Defense (1)]
Grieving Mandrake lvl20
Unruly Cell lvl3
Armored Rock lvl2 [Increase Party Defense (2)]
Charon of Hatred lvl22 [Covert Down (1)]
Scaled Chimera lvl1
Aspidochelone lvl2 [Decrease Enemy Defense (2)]
Scorn Black Wings lvl3 [Decrease Enemy Attack (3)]
Naga lvl1 [Slumbering Breath (1)]
Cruel Black Wings lvl1 [Decrease Enemy Defense (1)]

Rank B/B+
Poison Spit Frog + lvl1 [Venomous Breath (1)]
White Winged Soldier + lvl2 [Critical Rate Up (2)]
Horned Demon + lvl2 [Increase Party Attack (2)]
Fafnir Newborn + lvl1 [Decrease Enemy Attack (1)]
Arachne + lvl1 [Slumbering Breath (1)]
Charon lvl1 [Impulse Down (1)]
Undead Ammit [Slumbering Breath (2)]
Elder Tree Leshy lvl1 [Decrease Enemy Attack (1)]
Bunyip lvl 1 [Critical Rate Up (1)]
Menace Frog [Decrease Enemy Defense (1)]

Now, for the second part of this post. I have noticed that, occasionally, as I progress on standard missions I acquire free rank B summons. Can these summons only get me rank B/B+ or is there a slim chance at higher rarities? Also, is there a point where one acquires free rank A summons from mission progression?

Any post that can give me an approximate value on one of my monsters or answer my questions in the paragraph above this will be greatly appreciated. Thank you very much for your time.

Your unruly cell was worth a huge amount of EPs up until yesterday due to the labyrinth mission ending. Missed the boat a bit on getting rid of that one

Eh, pulled it in a Rank A summon I got from the event. Nothing to do about it unfortunately. I figure at this point it is only really worth evolution fodder.

Your best two cards right now are probably Aspid and Charon.

Rank B summons mean you can get at least a B monster or higher. You will most likely get A's 10 to 20% of the time. I have not seen any rare A's from these.