D&D 5E Please help out some new GM's with a few questions

[Sword of Spirit]

When you say 'limit' here, I assume you are not talking about enforcing an actual, hard numerical limit as an additional rule, since that's not something that anyone has proposed in the thread (and something that I would not particularly favor). I'm assuming that you instead mean the provision of in-game obstacles that make it nontrivial for the wizard PC to acquire spells beyond those they get 'for free'.

To clarify, I wasn't responding to any actual claims on this thread, but I have in the past on other threads, seen attitudes that seem to encourage ignoring the ability of wizards to scribe new spells into their spellbooks--which strikes me as overly limiting.

As far as making it non-trivial, I'm all for that. For instance, I wouldn't expect there to be arcane universities or mage's guilds where membership meant you can just copy the entire library of spells (even if you have the gp for it). As a DM, I would come up with some sort of good in-world explanation for why every wizardling from a wealthy family can't just buy all the spells. On the other hand, I'm in favor of membership in such an organization increasing your ability to acquire more spells, in the same manner as defeating wizard opponents and taking their spellbooks should. If everyone gets all the spells, then you lose that mechanic and play encouragement for the wizard to search for new spells. But if it's a game of "DM may I" to use that particular class feature--rather than operating in a plausible manner based on the assumed prevalence of wizards in your particular world, then I'm going to be fairly unhappy with the scenario.

 

[ElterAgo]

...
I like some of the suggestions for a creature. Phoenix seems like it might end up eventually wrecking the city. I like the sphinx. Though that seems like it might want to take over. Might go with a griffin though. Maybe magically altered to be more powerful/useful...

So almost nothing that session ended up going the way I expected. Loved it!

I decided to put 3 griffin eggs that were in the process of hatching. So the local ruler could start raising a flock. However the druid kept using call lightning on the caster next to an egg. Eventually I felt I had to rule that egg was fried.
Then the wizard grabbed one egg and ran off with it. So the local ruler has one to raise as his own personal mount, but no flock. And the wizard is determined that he intends to raise and train the one he snatched as his own mount.

I have no idea how much time, money, experts... to use for this. Any ideas?

 

[iserith]

So almost nothing that session ended up going the way I expected. Loved it!

I decided to put 3 griffin eggs that were in the process of hatching. So the local ruler could start raising a flock. However the druid kept using call lightning on the caster next to an egg. Eventually I felt I had to rule that egg was fried.

Top with salsa verde and cilantro and serve.

Then the wizard grabbed one egg and ran off with it. So the local ruler has one to raise as his own personal mount, but no flock. And the wizard is determined that he intends to raise and train the one he snatched as his own mount.

I have no idea how much time, money, experts... to use for this. Any ideas?

If it's anything like a horse (and why would it be?), then we're talking on the order of years before it's fully-grown. That might not suit your campaign, so some kind of fast maturation process is probably in order. You'll have to decide what's best for your campaign in this regard. I would likely treat this as a downtime activity, if you use those rules, and have it be on par with the cost of one or more skilled hirelings (2 gp/day) and some factor of regular stabling costs (5 sp/day). Then all you have to do is figure out the time it takes.