Now that we are davening b’yichidus, I heard that I may lain that week’s parasha from a chumash But may I say Hashem’s Name ? and if so , can it be counted towards shna’im mikra v’echad targum?
Yes you may definitely say H-shem’s name when reading the parsha, in fact you should specifically say H-shem’s name, as that is the correct way to read the posuk. You can count it as part of shanyim mikra.
Whenever someone says a posuk he may say shem H-shem. Regarding reading from a chumash see M:B 143-9. Regarding shanyim mikra it is brought in the name of R’ S. Kaminetsky shlit”a that doing shnayim mikra will suffice for this- obviously it can be counted for shayim mikra.
Rabbonim of the Beis Hora’a
Is there a mekor that you should say Hashem’s name Whenever you say a posuk?
Yes. but before getting to the actual mekoros, it sounds like when you are maavir sedra you don’t say H-shem’s name, so why is the Baal Koreh allowed to say it? Regardless the halacha is that whenever a person says a posuk, he is allowed to say it with H-shem’s name (See Kitzur Shulchan Aruch 6-3). In fact the Yaavetz says that when a rebbi read pesukim with the children he should specifically say it with H-shem’s name. R’ Moshe zt”l wrote Igros Moshe O:CH 2-56 that the reason for this is because if he says H-shem instead of saying H-shem’s name correctly he is saying the posuk incorrectly! (R’ Moshe doesn’t hold that it is an obligation like the Yaavetz, but it is definitely permitted. In fact according to a number of poskim it is even permitted to say H-shem’s name when reading a posuk learning, (and according to some even half a posuk!). There is controversy if one can say shem H-shem while reading gemora, (see sources).
As a side point according to what R’ Moshe wrote, it would be incorrect to read shnayim mikra without saying H-shem’s name as A-d-o…
Taz 521-2, M:B 215-14, Chayei Adam 5-2, NIshmas Adam ibid, Aruch Hashulchan 215-2