The laws of breaking bread are in O Ch 167 and with the exception of starting the cut are no different as mentioned there between Shabbos and weekday. See the same question asked at Ohr Someach.
The use of salt is mentioned in Seif 5 where the expression מלח או לפתן is used לפתן being something eaten with bread. There are situations in which salt may not be needed although there are mystical considerations to use it (see Torah musings). Again there is no difference between Shabbos and weekday. However as Torah musings says:
some have the custom to refrain from adding salt on Friday night
because no sacrifices were burned in the Temple at that time (see
Divrei Ha-Rav, p. 169; Piskei Teshuvos, vol. 2. 167:5).
Torah musings tries to deal with the fact that
many people only salt their bread on Shabbos but not during the week?
The only answer I can think of is social. Nowadays, people tend to eat
bread during the week as part of a sandwich. Often, a sandwich is
already salty. Therefore, people are not used to eating plain bread
during the week and, when they do, they do not think to salt it.
However, this explanation is insufficient because according to the
Rema, even a sandwich requires salt. Perhaps only our Shabbos tables
are compared to an altar. Or maybe the Rema’s custom is just to have
salt on the tables and not necessarily to put it on bread. But then
why do we salt challah?
The inconsistency is difficult to explain.
Aish instructs how to cut the bread on Shabbos.
Step 4 is
“The leader picks up both challahs, with the bottom one slightly
closer to him. Some leave the challah cover on during the blessing,
while others remove it at this point. The bottom challah is grazed
lightly with the knife."
On a weekday, an incision should be made in the loaf before the blessing at the place where it is well baked and after the blessing the loaf should be cut at that place. On Shabbos, when we need two whole loaves, it is better not to make a deep cut that might decrease the wholeness of one of the loaves - hence the reference to "grazing" in the Aish article. See O Ch 167 (1) MB 10 for the details.
See more detail from Aish here.