You can make a thought form in the form of a phoenix, though it will not be physical. Alternately, you can look into cultural lore all over the world and see if there are spirits or deities in phoenix form that you could work with.
not 100% sure what you mean. a thought form is an option, as mentioned above, possibly astral projection, or incorporating their energy into certain spells, yes. if you're asking for a spell to make you into a phoenix then no, i'm afraid there is none.
to repeat what's been said a thousand times or more, real spiritual magick is energy found in nature, focused by the caster in a direction, and used to achieve a goal such as luck, love, or protection. this energy is a force of nature, therefore it cannot go against nature. if you wish to cast a spell that a normal human cannot do [fly, teleport, shape-shift] then it cannot be done by magick.