Bilayers will reseal if broken.
Phospholipids vary by head group, tail length and saturation.
Bacteria will change lipid composition of their plasma membrane to maintain a constant membrane fluidity and adjust to temperature changes in the environment. Phospholipids have free lateral movement but cannot flip. Glycolipids are only found on the exoplasmic face. These may be removed using high salt or high or low pH. Integral membrane proteins have a hydrophobic component buried in the bilayer. Some of these proteins may be tethered to lipids.