How much do you have to spend right now? I'd say for now the head unit. Just gives a good foundation for the system and will control the amps. Then, I'd say speakers, and then subs.
And yes, that amp will match with the Perfects very nicely. Eclipse Titaniums are awesome. If you have the money to spend on one, I'd try to sell the vmaxes, maybe someone on this site is looking for one. Titaniums will run great on that amp as long as you're careful w/ the power, they tend to be underrated by a pretty large amount anyway.
I've run 1000+ RMS on one on a daily basis w/o problems, and when Eclipse recommends a system they recommend you use their 1000 RMS mono amp on that sub. I've seen people run 1500W RMS on them w/o problems, they were just careful enough to utilize it.