Hi Devilkiller,
Lets see,
#1 - Can Black Tentacles grapple incorporeal foes?
#2 - Would Black Tentacles attack a Spectral Hand even though it isn't technically a creature?
My Best Answer to both questions: No. Here is why...
A #1). The spell description of Black Tentacles gives no mention of being able to attack anything incorporeal, nor does Black Tentacles have the force descriptor (which would make further notation unnecessary). I would rule it cannot affect incorporeal creatures without the aid of another spell or a feat like Ectoplasmic Spell.
A #2). Black Tentacles specifically (and several times repeats) that it affects creatures, and never once mentions that the spell attacks other spells.
That said, a Black Tentacles would not attack a Spectral Hand or a Wall of Fire cast in the center of it. It could, however, attack creature conjured with Summon Monster, as the spell actually summons a physical creature.
