XPS 8960, can a front panel with optical slot be ordered?

Ordered from Dell -- almost certainly not.  The two systems appear to use the same case, and there are some with the optical bay slot on EBay at the moment if you think they're worth the asking price (at or over $100 just for the front bezel).

you can order the Dell 8950 front bezel to replace the 8960, or you can just use an external USB dvd. 

The black Dell bezel with odd slot is DP/N DRNVY 

Note the mod gets confused about this part.  the mod thought it is the odd bracket or bezel.  It is actually the case bezel with odd slot (see Dell part pic below).  In order to use an odd, you would need to order a standard oem dvd (bare without bracket) PLUS a proprietary DVD bezel designed for 8950.  This latter part was not easy to find at all.  Unless you plan to move your 8950 dvd w bracket to the 8960 (fitted with 8950 bezel w odd slot), do consider it would be hard to find a fitting dvd.

I was initially not in favor of a USB dvd, but after using one Dell model for so many times I find it very user friendly.  Really there is no absolute need to have an odd as external drive on a desktop pc.  the external dvd is just like an external hdd, plug n play.  It is also easier to load a disc if you place the XPS on your desk.  you do not even need to stand up to eject and load.  An external usb is handy for lazy user who sits in chair all day long.