Yes but to get an injector to spray small enough droplets to produce proper atomization would be extremely hard. Northwest Engineering own the patent to use the same technology as inkjet printer for this purpose.
Carb is still worth doing for small engine since even with carb efficiency you still get at least 15 - 20% more endurance out of the same amount of diesel compare to petrol
No, I do not know.
In the article I read, they wrote:
"The larger HFE delivers a significant increase in electrical power, generating higher horsepower and enabling the Aerosonde Mark 4.7 aircraft to carry additional payloads with greater electrical demands. Increased horsepower also contributes to improvements in aircraft performance including climb rate, dash speed, mission endurance and altitude performance." That is what caught my attention... but they do not specify which HFE they used. http://www.istockanalyst.com/article/viewiStockNews/articleid/4565253