I wouldn't turn those knobs on the RMX past 1/4 of the way there unles your preamp voltage is low... 800 watts RMS isn't a problem at all for the 2450 to push. I can cook my tumult with a rating of 1600W RMS with my buddy's RMX 1850, so just be careful. Peak is a meaningless figure.
As for the box, wait for someone else to respond. I'm not your man for that job :)