It was late. I actually meant to put in the point about blast radius, but I forgot as I was writing. Yes, the weapons were severely hampered by their lack of blast radius. I didn't say so much that they could win, but they certainly could have put up a much better fight. A little concern for geometric shapes, gravity, and basic physics could have made them last much longer.
Definitely. Speaking of bad tactical decisions though the droids could have easily just brought a few fighters with them and that would have taken care of the shields as they only seemed to block projectiles and the gungans didn't seem to have anti air weapons besides maybe a lucky shot with the catapult. Could have been annihilated without the infantry even having to march in.
The droids could have just sat outside and kept pounding the shield. They didn't NEED to go through the shield.