#1
is it ever a bad idea to bar 2 or 3 strings when sweep picking? like

|---------------12-17----|
|------------12-----------|
|---------13--------------|
|------14-----------------|
|---14--------------------|
|12-----------------------|

jerryc does it, but i'm not sure if he has the best techinque
#2
No! Major sweep. A shape I bar across the three strings like a rocking motion
But this goes up to 11
#4
It's never a bad idea to roll, or bar as you say (but stop saying bar, if you think bar, notes will run into each other), advanced sweep patterns require several fingers rolling, so I'd add that to your sweep repertoire.
Gear

Mesa Dual Rectifier
TC Electronic Polytune
T Rex MAB Overdrive
Boss NS-2
ESP Horizon NT See Thru Black (D Standard)

Celestial Wish on Youtube