Pretty sure shields collide with anything that impacts them. There's a few things like a proximity range and such which is designed to stop ships blundering into each other. Generally, the proximity radii are larger than shield radii so that ships don't crash into each other's shields. This can be seen when you have small frigates trying to get around your larger capital and keep raising shields and skirting to the side by a few pixels when they draw close, they're worried about their proximity although if it's set properly, they'd still have to get a bit closer before they crash into you.
As for using the shield like a weapon, that's not difficult. A large shield radius, efficient shields and a "heavy" ship will cause shields to do insane impact damage. A good example of weaponizing the ship itself exists in the oversized Neutrino hammership.