Welcome!
No face lift for X5///M for 2011. After that, who knows? Most BMW facelifts (if they occur) come during MY3 to MY4. I suspect there may be minor cosmetic changes over the next two of years, particularly wheel options and such, but the engine and chassis is new and will stick around for a while. The main facelift coming for 2011 will be for the non-M X5s which will be crossing over from naturally-aspirated to turbo land. Albeit nowhere near the power band of the M.

As for tuning, I'm sure Dinan will easily and safely squeeze 620+ hp from it (if 555 is not enough for ya). It will be a good 10-12 months before that happens, they like to extensively test their mods before release.