QUOTE
Increase Attribute is a great spell, but like so many of the boosting spells it is Physical, and will dissipate the instant you go astral. The limitation to Mana spells in the astral plane severely reduces the usefulness of Quickening for Free Spirits, one of whose greatest advantages is the ability to pop in and out of the material plane.
As a matter of fact, I thought that too. But someone here on dumpshock said, it is only a limitation on casting. If it is sustained it stays.
(Does make sense as a matter of fact. )
(Well, and as a matter of fact, there is no reason not to make it a mana spell afterall. The rules for that are in Streetmagic. You will even have less drain.)
On word to the qualities:
I think you should make it a GM call in any case. There are just some thing not making any thing (celerity for a free spirit ?)
Mentor spirit on the other hand is a very fitting.
(It would even fit to make it a must have)