Ratings, currency and proficiency
A Cirrus is a type of aeroplane, not a rating. The SR series sits within the ordinary single-engine land privileges — but the aircraft's capability makes some of the optional things much less optional.
Learning ab initio in one
It's done, and some schools are built around it. It's a faster aircraft with a higher approach speed than a traditional trainer, which means less time to think in the circuit, and it is more expensive per hour. The counter-argument is that a student who will go on to own one avoids a transition later. Both positions are defensible; it's a conversation for an instructor who knows your situation.
The instrument rating
This is the one that matters. A well-equipped SR22 is a genuine cross-country machine, which means it will readily take you into weather that a VFR-only pilot should not be in. Inadvertent flight into IMC by a non-instrument-rated pilot is one of the classic fatal scenarios in high-performance singles, and it is one of the scenarios that CAPS training explicitly addresses. If the plan is to use the aircraft for travel, the instrument rating is part of the plan.
Ground study that actually helps
Airspace is the part most students find hardest to hold in their head, because a sectional is a flat drawing of something shaped like a wedding cake. vfr3d.com renders VFR sectionals, airspace and terrain in three dimensions, which makes the shelves and floors legible in a way the paper chart never quite manages. runwayinuse.com is useful in the other direction — it works out which runway an airport is currently using from ATIS, wind, ADS-B traffic and NOTAMs, and shows its evidence. Both are study and situational-awareness aids: neither is a navigation source, and neither substitutes for current official charts and publications or your preflight briefing.
Staying proficient
Legal currency and actual proficiency are different things, and the gap is wider in a capable aircraft flown occasionally. Recurrent training — the manufacturer's recurrent syllabus, COPA's CPPP, or regular work with a CSIP — exists because the first hour back after three months off is not the hour to discover what you've lost. Insurers frequently require an annual recurrent flight, which is a floor rather than a standard.