At first glance, this seems a low-intensity story, which would usually earn someone 5 xp. Pratice also works. It is a bit of a stretch to gain 10 xp in that season, but the narrative approach is flexible so if you want those xp, then feel free to do that. In the end, things should average out, so gaining 10 xp in that season means you have less xp available if you wanted to read a high-quality summa later that year.
The same is true with your later question about Twilight Points gained. Less intense stories can be used to justify gaining fewer Twilight points, but that should also mean less xp gained on average. For example, my path during Clusius narrative resulted in an average xp/year that was significantly lower than 45 (even accounting for lab seasons), so I decided it made sense for him to have gained fewer Twilight Points than average.
Joining a covenant or not is a narrative choice. It should make sense in the setting, so as Rafael mentioned the Alps would not accept your maga because she is too young, for example.
Whether you join a covenant or not, you should integrate a season of unproductive endeavours pretty much every year. This often represent services provided to your hosting covenant, either as a member or a visitor. You can sometimes substitute that with raw vis, but that would come out of any vis you accumulate during those years (or from a personal vis source).
This is a slightly higher-powered saga that usual, so a Personal Vis Source would yield up to 6 pawns/year for most Forms (though Corpus or Vim should probably be a bit lower) or 3 pawns/year for a Technique.
The 3 pawns/year from the guidelines is really not "automatic", but rather represents what can be gained from stories, for some specific services rendered to covenants, vis hunts, etc. This is the currency you can use if you want to pay for a longevity ritual (either created yourself or from someone else), enchanting items, binding a familiar, etc. Much like xp, higher/lower average vis collected over the years should mean more/less Twilight Points gained as well.
At least one season to find and befriend the potential familiar. That season is less productive than a regular story, so a maximum of 5 xp can be gained. If your narrative would indicate an unsuccessful search for that season, than regular story xp can be gained.
You need to spend the normal time in the lab to bind it and the vis comes out of what you accumulated from stories, services and such (as stated above). If what you collected isn't of the right Arts, you can make trades in the narrative. The trade can be with a host covenant or individual, thus not subject to the Mercere exchange rate, or you can work the narrative so that you found more vis but "wasted" some of it doing the exchange (it is the net quantity of vis that is considered in the guidelines).
These Twilight Points can represent spell botches that didn't lead to a Twilight experience, an actual Twilight experience, or being subjected to a powerful magical effect (which can you no long-term benefit, like being teleported somewhere).
Anything else, such as having a longevity ritual or getting someone to cast a stats-raising ritual on you, should be added on top of the guidelines.
Making your own longevity ritual is simply a season in the lab and spending the corresponding vis.
Getting someone to create a longevity ritual for you is expensive -- at least 1 pawn for 5 points of the lab total, plus the cost of casting the ritual itself. So for example, getting someone to create a level 50 longevity ritual (giving +10 bonus) when she is 29 years old would cost her 50 pawns, plus 6 pawns to cast the ritual itself.
No actual spending needed. This is simply part of the narrative. The actual xp gained comes out of the what is allowed by the guidelines (45 xp per year).