I have decided to do a song that consists of numerous hammerings throughout. Do you think that it is possible, for the meantime, (while i work on them) to pluck as a substituition? Will there be any important changes?
IMHO it is perfectly acceptable. the tone will be slightly different. hammers and pull-offs will eventually make your life easier once you get comfortable with them.
One exercise I do is play my warm-up scales with hammers and pull-offs. I start up the fretboard (eg C on 5th fret on low G string) and try not to pluck anything — hammer going up, pull-off going down (hammer the 1st note on the lower-toned string)