JBauer -
I submitted everything prior to the holidays through PVS International. Total fees were $293 ($193 embassy fee, $75 PVS fee, $25 return two-day shipping) + fedex to send everything in.
PVS International website lays out all of the info for what you need. Yes, you need an "invitation" (visa support). I'm staying at the W, and they provided the visa support - I just emailed the hotel and they sent a form to fill out. PVS International will also provide for additional fee (and if I cancel my hotel reservation for some reason before I go, the company that the hotel works with will charge me).
Still waiting to get things back from PVS, so hoping I did everything right!
And quick update on my earlier troubles if anyone was curious - it was my work network that was blocking my access to the application form for some reason. Was able to get to it from home just fine.