Flash for wedding photography

Yes to all those questions .... the Pentax term for the modern auto-exposure system is P-TTL ('Pre-flash TTL).
The flash head zooms out to 16mm, and the wide panel extends this to 14mm. You could use the panel even with longer focal lenghts to spread the light, but be aware that the zoom head will automatically come back to 16mm, so you might lose light and power.

There is also a catch-light panel included to push some light forward for the eyes when the rest is bouncing up.

Don't forget, there's also 'Auto'-flash mode ('A'), which is the older system before TTL, and this uses a sensor on the front of the flash to measure the light coming back and stop the flash ... this is very useful and accurate I find, and allows us to use auto-exposure for flash with 'A' series lenses (where P-TTL won't work).

Thanks. I'm in the market to buy one so, will check here before Ebay etc.

£349 new and £199 2nd hand from a quick glance on Ebay. That's ok.