Here are some tips
1) If possible increases the input voltage from 12V to 24V or 48V.
The higher is the battery voltage, less current need to switch in stage push-pull DC 400V.
If possible, use a PWM sinusoidal modulation in the H-bridge to increase the total efficiency (= longer battery life) and
thus reduce the output filter.
2) 20..50kHz is a good choice to limit the switching losses and for a wide choice of MOSFETs, DIODEs and ferrites for transformers / inductors.
3) The driving of the MOSFET is simpler. I use IGBTs for power - voltages even higher than 3kW -1000V
4) For simplicity, I prefer the push-pull stage for DC-DC
5) There are several IC drivers to drive the arms of the bridge-H, for example, IR2110 / IR2113.
Alternatively you can use a transformer to drive to the gates of the high side.
6) The configuration you described is "canonical" on which much literature is available.
Finally as a last resource for learning: REVERSE ENGINEERING !!!
Good luck !
More tips on Topic: Sinewave Inverter With Pic:http://www.sonsivri.to/forum/index.php?topic=362.0