When you are creating a Psion character and you roll a Talent you don't already have, does the character automatically get that new one?
No. 2016 pg. 203, under Using the Psion Career:
When rolling on the Service skills table, if the Psion rolls the skill for a talent he does not yet possess, he may make another roll to acquire that talent.
That's pretty clear. But read literally it's only the Service table. You're often well advised to roll on your Assignment table, which is likely to raise a Talent you already have, and if you don't already have it doesn't have the limiter.
So practically, Service Skills is repurposed for something different than in most other careers. But keep in mind anyone who's rolled a Psionic life event or found an Institute has had one opportunity to test for every Talent already, so there's some kind of overall balance if you squint.
It's not what you're asking, but I also read the section on acquiring Talents that says you gain powers at 0 to apply here as well. That's not the only possible explanation, but given Mongoose's predilection for not restating rules in full everywhere I think it's a reasonable reading.
And if you take a Term in Psion, can you start University after that Term?
[Pre-career Education] ... can be delayed up until the third term if a term or two in a career is desired.
I've never seen anyone choose to do so, so I had to look it up, but yes.
A side note, by RAW a player can't take a Psion career without GM permission or rolling a qualifying life event, but otherwise yes. Note that Psion is a "gain basic training from your Assignment table not Service skills" career.
