How do the areas of the emitter, base and collector affect their respective currents?
A standard method to manipulate the behaviour of bipolar is to include INTEGER scale factors on the schematic used by the simulator and in defining the silicon layout.

Doubling the emitter-area, such as laying down TWO devices adjacent (for thermal tracking), while operating at the same total current, reduces the current density and thus reduces the emitter-base voltage by 18 milliVolts. Also, the allowed peak current will have doubled, should you expect heating issues or beta-collapse at higher currents.

Bandgap voltage references often use 2x or 4x or even 100x. I've reverse-engineered some older ICs that used 100:1 collection of diodes, where the 100:1 allows

log2(100) * 18 milliVolts 

as the working delta_Voltage for the bias-generator design.