My english is bad, i know. This is not my native language.
Make a good endermen farm in the end, get 2 K and 3 N2 cells from 16 enderpearl dusts (automate it), 2 K+2 N2+3 Compressed Air -> 10 Saltpetre + empty cells (in electric crafting table). The excess N2 can be used for something else (glyceryn)..
@share machine casings, yes you can share machine casings between all GT machines (implosion compressor, sawmill, industrial blast furnace, grinder, vacuum freezer).