Glass, probably not, so long as its smooth. If it looks like the surface of the moon, its porosity (bad).
One crater at the end of your weld, means you took your foot off the pedal too fast. As the puddle cools, it contracts, and leaves a crater (same reason why castings leave extra metal in the sprue). You may need to overfill by one extra drop of filler, as you start to lift off the pedal, and watch it contract back to level when solid.
If you're working with clean tubing, with the mill scale sanded off, and no oils on the surface, you won't get porosity. Mild steel is really cooperative.
Funky colors, could mean problem with your shielding gas (probably bad), or a lack of postflow (not as bad on mild steel, but still not ideal).
You need to keep the torch in place, until the postflow stops. Maybe need to adjust your postflow timer, or check for argon leaks.
What do you mean by the 1/16" filler being hard to get uniform? Don't expect a perfectly smooth surface. A stack of dimes is ideal.
A picture's worth 1000 words.
BTW, it sounds like you're using a foot pedal.
80 amps might be a higher setting than you want. I normally set my max current only a little higher than the numbers by the book (not double).
So, with .035", say, 45A might work best. With pedal control, you want to set your max current to the highest you will need for that weld.
Basically, you can then choose to put your foot down, and cruise along, and also have the finest control over current.