RE. Bardic magic.
Looking at common magic it would be very easy to interpret many of the spells as useable by a bard. Of course the lowest % score of sing, instrument and the common spell would have to be used to cast the magic.
Taking fanaticism as an example, take everything such as cast time, magnitute and duration as written on p166 Core Rules but make it affect allies within earshot up his charisma in number and the bard must continue to sing for the entire duration of the spell or it halts (and possibly play an instrument if you want to make life hard, which would be my choice as we are making common magic quite poweful here!). The spell may also endure briefly if bard has particularly high charisma, perhaps on par with the advancement roll modifier in combat actions.
After the initially listed casting time has expired the bard can weave another spell into the same song using the same rules. If the bard wishes only to cast upon one target (including himself) he may forgo the need for an instrument and thus be able to engage in combat as long as he is not interrupted my a major wound or some other method of silencing him.
Given the disadvantages of non interrupted singing & playing to maintain a spell and the obvious lack of ability to stealth or do a sneaky pre-casting, as well as the need for multiple skills required (sing/instrument/spell) I think the power enhancement by multi targeting the common spells is reasonable.
However this does tend to make the bard player a buff bot if targeting a group, so developing new spells would be advantageous in allowing the bard to play a more active role.
All these common magics would work, with those marked * working only on the bard himself.
beast call
bestial enhancement
becalm
befuddle
countermagic
demoralise
endurance
entertainers smile
fanaticism
glamour
golden tongue*
mobility
slow
spirit bane
thunders voice*
vigour
Lesser effect spells could be developed to work on whole armies to improve morale, vigour or fervour.
