On a legacy PROFIBUS DP network, does this drive connect directly?

PROFIBUS DP is onboard, so the 6SL3230-3YE10-0AP0 joins an existing Profibus controller as a native node — no protocol gateway and no option card. For industrial Ethernet the F-suffix variant applies; for serial or BMS buses the B-suffix variant applies.

The cabinet needs C2 EMC — do I add an external filter?

This unit ships with the C2 filter built in and tested at the factory, so there is no external filter module to source or wire. An unfiltered variant would push that cost and a commissioning step onto your build.

What overload rating applies to pump and fan duty?

Pump and fan loads are variable-torque, so the drive is rated at Low Overload: 110% of rated current for 60 s. At 0.75 kW that is 2.1 A continuous with headroom for start-up surges, in a 73 x 232 x 209 mm IP20 frame.