OK here is my first draft. I've tried to keep it pretty simple. Also Ive decided to start out underpowered, its easy to add stuff afterwards- powerlevel naturally also depends on what spirit powers are available.
Free spirit with priority system.
Race:
A: Free spirit (4)
B: Free spirit (0)
C: N/A
D: N/A
E: N/A
Attributes, skills and resources:
As normal
Special:
A: magic 4 and 7 spirit powers/spells
B: 3 magic and 4 spirit powers/spells
C: 2 magic and 1 spirit power/spell
D: N/A
E: N/A
This gives the spirit around the same priority choices as a troll mage/technomancer
Attribute scores:
Choose one physical attribute and increase minimum and maximum by 2, choose any other attribute physical or mental and increase it's minimum and maximum by 1 ( one attribute becomes 3-8 and the other 2-7). The rest are 1-6 attributes
These 2 attributes are henceforth known as its primary attributes. All physical and mental attributes MUST be within +-1 of the spirits magic score. Except it's primary attributes which may surpass it, up to racial maximum. Regardless of magic score.
The spirit also has force and essence. These are always the same as its magic score. Aaand they have edge as normal.
Spirit being: all free spirits are magicians. Choose a tradition for the free spirit (drain attributes and concept).
Gain +2 to all social rolls against other spirits.
Powers: sapience, astral form, materialization, banishing resistance, realistic form. + more according to the priority table.
Your initiative is reaction + intuition + 2d6 on the physical plane
And when you "die" you are just disrupted.
As a free spirit you can never use the conjuring or tasking skills. Nor can you bond foci or use 'ware. (not bonding was from 4th edition, maybe they should be able to now?)
Free spirits may take most qualities within reason.
And there are some unique spirit qualities also
Unearthly form +x karma: the spirit looses it's realistic form,
leveraged +x karma: someone has a copy of your spirit formula. You must sometimes perform tasks on their behalf
Possession - x karma: instead of materialization you have the possession power,
dual forms -xx karma: you have both materlization and possession powers,
mimic + karma: you are addicted to BTLs or drugs etc. They don't affect you but costs cash and may lead to odd situations, especially when you think you are having a psykosis.
Spirit powers : most likely some long list of powers. But a bunch of those powers would be solely for Npcs.
Regarding karma. As Jack wrote spirits don't usually gain karma on their own. So they might need a pact or something else for that. My gut feeling tells me that Jacks pact might be a bit too restrictive.
Maybe just skip it?