A Question about Spell Sovereign (3.5)

[Zaydos]

I've been looking at Dragon Magazine #357 and I have a few questions about Spell Sovereigns. They look interesting, and like they could be a fun back up character or NPC in some game. So the question is:
#1: Is the prestige class worth it; ignoring comparisons to Incanatrix and Initiate of the Sevenfold Veil or Shadowcrafter Mage (those leave a bad taste in my mouth probably because those are the ones I say no to as a DM), but it loses 3 CL and is what it gains worth it? If I go the NPC route I could change the class if they aren't, and if it is too big of a hit as a player I'd not play it (unless everyone else was woefully unoptimized... which might happen).

#2: Their living spell familiar. It says it has the normal HD of a living spell, but a living spell normally has HD = to its caster level and is not limited to minimum for it's spell level. It would be cheesey to up it, but could you/should it use your CL?

#3: What are some good spells to choose for your living spell familiar? The first thing I could think of was Lesser Orb (for Lv 1) and Enervate (for Lv 4). But at Lv 6 the Lesser Orb is weak unless its CL = yours so see #2 (even then it's just blasting). So what would be a good spell of each level 1 through 4.

#4: Several of its abilities rely on the presence of living spells. As an NPC this means give him living spell minions. But what about as a PC how much power does it lose if they aren't common/gain if they are?

Thank you in advance.

[Mooch]

not sure on the specifics of this prc but i would think a good spell would be one of the fog spells using a living spell with this would be great imagine a solid fog that would chase down the targets or move to provide you concealment etc

with respect to the 3 lost caster levels that will be detrimental as you would be a whole spell level behind another caster

[Zaydos]

Thanks. I've actually been wondering all day about how Living Solid Fog would work, or Living Evard's Black Tentacles.