If we go by weightlifting, human Strength caps at 4 since (really impressive) people can lift 400lbs but can't lift 800lbs. If we apply that as a standard, a 4 in an Ability is "best humanly possible", anything up is actively superhuman. That said, there's a lot of flex since the source medium is inherently unrealistic and nobody really tries to put a "human maximum" on mental scores.
And of course, you have magic. Half the issue vanishes instantly if you buy your Stamina as a power, because that instantly describes why a teenager is harder to hurt than solid stone.
The other half of the issue, one which is significantly more opinion-based, is the distribution of your Abilities. Right now, they look something like this if we put them in a graph:
This "might seem like the a min-maxing Pathfinder wizard", as you put it. There's a total lack of investment in some Abilities and a very heavy investment in others. This isn't wrong, necessarily, but it does raise questions about why they're perfectly average (or perfectly slightly below average) in all ways except the ways they're stellar.
An easy fix is to spread things out in the -1 to 2 range. Say, STR and PRE to -1, AGI and DEX to 1, everything else at 0 or 7 as it was. It doesn't really change things that much, but it feels more "detailed", for lack of a better term.
> Thematic utility is not something I had considered beyond useful spells he might have to be of some use to the group. I will work on that.
I was speaking of thematic unity, not utility, but I didn't really explain it well. My stance was that the magical powers didn't seem to have any common thread beyond "magic", mainly because all I had to go off of was the raw effect.
If you put names that share a theme on the powers (say "Eldritch Force Evocation", "Walk Unseen Horizons", "Darkness of Worlds Beyond", etc) that indicate a common method or source of power, it makes the magic "pop" because it suggests how the magic works beyond just "it's magic".
Basically I'm suggesting you apply another descriptor to all the magical powers beyond just "magic".
> Is there a certain/typical number of skill ranks that should be spent?
No typical number of points, but I generally feel any given character should have invested in at least a couple skills to add some depth. Even small investments can add a lot of character to a character.
It's also a general recommendation to have some points in a social skill unless your character is a bit of a social wreck. Which is fine too!
> Just wondering if there are craft skill equivalents in this game? I would like to make him an artist, just to round out the character, but am not sure how that would be accomplished.
Expertise covers what would be Craft and Profession in Pathfinder. So Expertise: Artist would do it.
> Can a Ritual be started and stored (for lack of a better word) and left until the last moment to finish off when appropriate?
I don't believe you can "mostly finish" a ritual and sit on it, but I see no reason you couldn't prepare everything and do all the research in advance.