The reason why a printing press is not kosher for sifrei torah, is because it has the din of chok tuchos. Other problems include that of lishmah and ksidron ( by a sheim hashem). But it is actually a machlokes the shach and the taz about the kashrus of a Megillah made by a printing press. All the achronim pasken that is is assur and look in Mishnas hasofer Perek 28 that says you are mechuyav to put such a megillah in genizah.
On shabbos you are oiver kesivah midoiraysa even without a maaseh kesivah .The poskim do not pasken like that ran
The shitas chazon ish about electricity has no shayachos that it is connected to a house. His shitah can be found in Chazon Ish Orach Chaim Siman 50 ois 9. He says that completing the circut in itself is boneh medoiraysah. It sounds like a big chiddush but when you learn boneh you see it makes a lot of sense. The Minchas yitzchok argues on this chiddussh. For a halachik understanding of the problems with chashmal and the shita of the chazon ish, look in tzitz eliezer 1:20, Sefer Meorei eish 2 vol.(from Reb Shlomo zalman) MInchas Shlomo 1 :11. Rov haposkim agree to the chazon ish and hold that turning on anv electric thing is deoraysah. Reb Shlomo zalman has an arichus about talking into a telephone that is already on if it is assur midrabanan or mideraysah ayin shum Vdok.
About the rabbonims understanding of electricity, look in meorei eish chelek 2 (5770 ed.) perek 13 and MInchas Shlomo 1:9 and 1:10. In both places reb shlomo zalman explains the metzius of the entire inyan before hondling the psak. On the ha’ara on bottom it says that before he began to write about the inyan he spoke to many electricians etc. to understand the metzius completely.
Now about writing on a computer connected to a screen look in Shevet Halevi 6:37 HE says it is assur mideroisah because it is ksav hameskayaim and you need a new peulah to erase. look over there where he assures typing on chol hamoed etc.