Need help attempting to understand and find certain transformer
It's commonplace for a transformer to have a winding described as x-0-x, the 0 terminal is simply a centre tap. This makes a full bridge balanced output about ground easy to acheive. When used as the primary in an inverter, the centre tap will typically be wired to the +ve terminal, with either end pulled down to ground.

A 'normal' mains transformer core will be very lossy at 400Hz. These things are built down to a price, for a specification. Good low loss operation at 400Hz, as in aircraft transformers, requires very thin (expensive) iron laminations. The lams used for 50/60Hz transformers are much thicker.