I think those are the Podium E-1200C, which is the bottom-left cabinet on this URL:
http://www.podiumproaudio.com/podiumproaudioproduct/threeway.html
These are like speakers for your home, and are not suitable for sound reinforcement use. The stated sensitivity is 92dB, where as professional speakers are often around 100dB sensitivity (more is better.) For example, the ~$200 Kustom KSC 215H (not what most people call "professional," but I like them) claim 98dB sensitivity. That 6dB difference (98 - 92 == 6) means, when driven with the same amount of amp power, the Kustom cabinet will produce four times (6dB) more sound energy. This is more than enough for a listener to notice, and but is not quite double the apparent volume to the listener (10dB or ten times as much sound energy.)
So basically, those speakers are suitable for your home, but as far as a bar/club rig, they are junk.
As to the issue of 30kHz signal reproduction, the tweeters in those cabinets may really be able to do that; but it doesn't matter because you can't hear that. There are some studies that suggest listeners can tell a difference if they pay close attention to A/B playback of a recording with > 20kHz content and without; but recorded music doesn't contain this material, live instruments produce it only as harmonics, and microphones don't pick it up. So as to the 30kHz thing, who cares.
As far as what amp you want to power those cabinets, I am surprised the RMS rating of 250 watts is so close to the peak rating of 500 watts; but as such, select an amp that produces at least 500 watts into an 8 ohm load. Note that with these particular speakers, my guess is they will overheat before they will be damaged by over-excursion or infrequent amp clipping; and you might even want to de-rate that RMS value a little if the club is packed with sweaty customers and the ambient temperature is 85F.
But honestly, tell your buddy those speakers are trash. Buy some different ones. Then worry about amps.