That 600 mOhm limits the AC ripple current before self-heating becomes a concern. For a 10 V rated cap, the derating margin is standard practice for tantalum to avoid surge failures. The molded case handles the mechanical stress of temperature cycling better than a conformal-coated chip.
2312 (6032 Metric) case, size code W — 6.00 mm × 3.20 mm × 1.50 mm seated height. That is a standard low-profile tantalum footprint; the 1.5 mm height clears most mezzanine card gaps. The ±20% tolerance is typical for tantalum; if the circuit needs tighter tolerance, a polymer or ceramic alternative would be the move.