Spirits start-off with a basic power set, and the summoner can add one optional power for every 3 full points of force. At force 6, for example, I can summon a spirit with the basic set plus two from the optional set. The optional set of powers is different for each spirit, so as an example you can't give a fire elemental the venom power (which would make it even more sick in melee). I could, however, give a force 6 beast spirit the Venom and Natural Weapon powers, making it perhaps even more effective than a force 6 fire elemental.

The spirit of man has an exceptionally interesting optional power, as you can give it the innate spell power of any spell your character knows.

Everybody that sees the elephant going by will consciously suppress it as a figment of their imagination... similar to the pink elephant walking by scenario my friends have joked about.

Summoner chooses, page 294 in the Spirits overview:

A couple of glitches here though:

WTF gave you that idea? It is casting a spell just as if it was a magician/mystic adept. If you are talking about the Spell Sustaining service on page 179 that is refering to the summoner not suffering the dice penalty.

The second glitch:

The problem here is whether or not the spirit of man summoned by the hermetic tradition can even cast anything other than a Combat spell. Though that is open to some interpretation.

Of course the alternative is for the magician to summon the oppropriate spirit type for whatever tradition you have. This is more useful in that all traditions could do this, not jut ones that can summon spirit types able to cast spells. The magician can then cast the spell and transfer the grunt work to the spirit via Spell Sustaining service. The magician still has to deal with the drain themselves, but using another service for Aid Sorcery might help there (depending on interpretation always, or only if they have a Spellcasting focus).

EDIT: A Spell Binding service might also be an option. Though there are drawbacks to this in that repeated use is likely to incur the ire of spirits (GM options). Something else is whether the spirit really needs to have concealment. The safe move is to have him wait at his metaplanar happy home. Wards? Well i'm going to start another thread about this....

I was going for no drain based off what it worked like in SR3, which is why I said I wasn't so sure about it.

By the rules, spirits of man can have "Innate Spell (any one spell known by the summoner)". Note that no limitations are set on spell school by tradition, although some people might potentially house rule it that way. Even if it were limited, hermetics would still be able to do the wired reflexes spirit whilst shamans could do shapeshifting spirits and similar.