so after taking a few levels in something to meet the skill and will requirements a Neraphim could go straight for this class with no other tricks?
They are outsiders. You have to use the entry tricks I listed to add the evil subtype.
As for summoning tricks, dragon magazine 302 has additional summoning rules. You can pretty much summon any outsider and they allow you to add templates to make the creatures outsiders. Summon up a Pleasure Devil from the fiendish codex 2, page 134. They have the ability to temporarily take over a creature and take a full round of actions with that creature. So you possess you meat of choice, summon in pleasure demons with a level 8 or 9 spell, then have the pleasure demons use their possession ability on your meat. Your possessed target will get his own set of actions and up to 3 more if you summon 3 devils. And that is only the first round, the following round you can cast a different spell while your meat takes 4 more actions. I guess it gets worse if you compound it by possessing a Chronotyryns.
The additional summoning rules also make fiendform alot more fun. I think you can pick devil, demon, or fiendish creature you could turn into with a summon monster level 4 spell. Still only a CR of 3, but I am sure there is something of interest that could be done.