Can we advance companions on the seasonal planner instead if we so choose? I prefer that over static xp.
Yes, if you are mindful of your obligations and free seasons.
I don't think I've gotten a clear answer from you about how many free seasons companions have. Bernhard is committed to assisting Vulc as a top priority, but that doesn't always take two seasons a year. If Vulc needs him for less than two seasons, are all of the other seasons considered free?
If the covenant doesn't pay companions for their time (and I haven't seen any mention that they do) then the covenant has no claim on a companion's time.
Paying for their time is implied in the Inhabitants Points system from Covenants. They live a more lavish lifestyle.
Fightmaster: I'd say don't bother about it.
It stands to reason that no Verditius will sell items 2 seasons per year, every year. Even 1 per year may seem a stretch. So if you base venditors on that, you're toast, and can easily come up with "Why, unlike every other companion, doesn't mine have 4 free season per year, with only 1 of work every 3?"
I'd say just assume that he does something for work.
He may be working for multiple verditius, maintaining his contacts, keeping in touch with the market, doing mundane trade, enquiring who could be interested by what by vulcanus, who'd pay more for what, whatever.
Even after they enter play? If so, this seems strange, I'd have thought these would rather have had to be negociated with the Magi (meaning it costs no XP to the companion, but costs time and/or vis to the magi/covenant)
if kept to a minimum, which it likely will be, it is not disruptive. It can be presumed that the covenant can import goods from the outside. Simple items; 20qp for a magic shield, 25 to 30 for a sword, 20 to 40 for magic armor, 10 for a magic lantern, stuff like that. In the old days we used to have a ton of the stuff and I gave it out freely. Now it will cost you. Mind you, this is only for off stage advancement covering a few years.
And there is such a small handful of grogs run by player characters it easily monitored.
And in game, as in you have to work it out roleplaying, grogs can certainly work out side deals of their own earning items as rewards for services and adventures played out. They can keep the xp and have the item too.
And it is much cheaper that way. Remember, the qp value works out to something like three times the equivalent amount of vis.
Ok! 
Then again maybe you are right. It depends on who wants to do what with it.
Well, other things: In summer 1233, she gifts 3 Unerring Daggers (the version that needs to penetrate) to the covenant.
She's thinking of creating visual + audio variants of the Spider Signal to give to the guards, but this will have to wait a little.
If vulcanus approves, she'd also like to put planks (have a wooden floor, with some planks being trapped) and strings of cloth as traps in the Vault which cast Illusions, Call to Slumber or dispell parma when touched. Likewise in the Library, with Vocis consent. Hum... Since some books had wooden covers, she could probably do a trapped book, too.
Just back from a travel weekend, trying to catch up...
Let me know what you have in mind and Vocis could do it. I realize Arachne can make charged items much more efficiently, but Vocis could make several lesser CrIm enchantments in one season. His lab score is in the low 60s.
We'd have to be very careful doing this in the library. If the trapped planks aren't selective, we'd have areas in the library that people would just have to avoid. That gets awkward, even with the library spells from Covenants that let you teleport books. Same with trapping books.
Btw, is Vulc still planning to enchant that big protective item for the library?
She's thinking of something simple.
Like a spider that emits a loud sound, or one that create the illusion of a big arrow where it's activated. Pretty simple, and low level (05).
It'd probably be a waste of time for vocis to create these: he'd waste an entire season on it, whereas Arachne can just craft some in the 10 "free" days per season we have, without it impacting her lab work.
She'll appreciate the proposal, though, and thank Vocis. Now, such a lab score...
That's the problem with traps, of course.
Trapped books are easier, since we just need to avoid them.
She could make the traps selective (with a +3 for restricted effect), but I don't believe you can do a "magi of andorra" list that encompasses any future magi, not unless you use a linked trigger (which she can't do on a charged item): IIRC, you must make a specific list, and it can't be changed.
But this'd allow the people on the list to walk the trapped planks without activating them.