yes it will print petg.

As to the slic3r question. You've pretty much answered it yourself.
It is possible, but difficult.
And no i never managed to get it to work, bought simplify3d instead and used makerware desktop until then and occasionally still do for dual material prints.

slic3r produces gcode files - makerbot clones don't use neat gcode files, they are converted to .x3g files that the printer reads from.

In makerware and simplify 3d this is done seamlessly within the program. With cura & slic3r you have to run the gcode through a convertor called gpx.
There are also changes that have to be made to the startup gcode, gpx settings etc - it's not straightforward. But there are a few guides online, the couple I tride way back when did not work for me :-)