the orals are pretty hard to dissolve into liquid solution, as opposed to normal steroids that have an ester attached. the ester is actually a lipid chain that makes them more lipophilic, or dissolve easier in oils. the orals need a lot of alcohol for them to be dissolved into a solution which makes for painful injections or crashing of the solutions.
i don't know if it makes them easier on the liver, i do not believe it does. in my opinion, the only difference with injecting an oral, is it reduces the cost by a slight margin (since you lose less steroid) and increases the half life as an oil depot takes a little bit longer to dissipate in the body.
the process of methylating the steroids changes the way the steroid works in the body so, yes, injectable orals are the exact same as edible orals (the orals i buy are in injectable form, however, i just eat it since i don't want to deal with pip).