Like Spectre771, I assume Merging is supposed to say "Caster can merge into a solid, inanimate material."
The differences between the spells are:
* Phasing cannot be used to enter magical materials, Merging can
* Phasing permits movement, Merging does not
* The duration of Merging is ten times longer
So phasing lets you pass through, while merging lets you remain concealed.
Since the spell doesn't say anything about bleeding or other physical conditions, I would assume they continue to affect you. Your phased blood continues to leave your phased veins.