Can Birchos Hashachar be said at night before going to sleep?

L’chatchilah, one should recite all of the Birchos Hashachar before davening. Otherwise, they should be said after Shacharis, before the end of zman tefilah. Some Achronim only allow them to be recited until chatzos (midday). Others are lenient and permit them to be said in the afternoon. There is even an opinion which permits them to be said after nightfall, up until the time a person goes to sleep. We do not protest when others rely on these opinions.

סימן נב, סעיף א, ס"ק י, וביה"ל ד"ה כל; וראה ביאורים ומוספים דרשו, 9

Can Elokai Neshama be recited after davening?

According to some Achronim, if one did not say Elokai Neshama before davening, he may not say it after davening. This is because it is possible that one may have been yotzei by saying Mechaye Meisim, a brocha with a similar theme, in Shemoneh Esrei. Others disagree, since Mechaye Meisim refers to the future resurrection of the dead as opposed to the daily revival discussed in Elokai Neshama. To avoid this uncertainty, one should have in mind not to exempt Elokai Neshama when saying Mechaye Meisim. If a person did not have this in mind, he should go to sleep. Upon arising, he can say Elokai Neshama, since some hold that it is recited after a daytime sleep.

סימן נב, ס"ק ט וביה"ל ד"ה ומכל

Can one answer to Kedusha while in the middle of Yishtabach?

The brocha of Yishtabach contains fifteen terms praising Hakodosh Boruch Hu. Some poskim do not include the words brochos v’hodaos and count only thirteen praises. The praises must be recited successively; one who interrupts them is subject to punishment. It is not necessary to recite them all in the same breath. Responding to Kaddish and Kedusha is permitted in the middle of the praises, but one should go back to the beginning of the praises afterwards in order to the recite them consecutively.

סימן נג, ס"ק א; ביאורים ומוספים דרשו, 6-5

• Tefilah b’tzibur is a critical component of davening. As such, a latecomer to shul who would have to daven Shemoneh Esrei on his own if he were to proceed with the whole davening may skip parts of Pesukei D’zimrah.

• A person may only skip if he will not have the opportunity to daven along with the tzibur at a later minyan.

• The poskim disagree about whether a woman should skip in order to daven with the tzibur.

• Is it necessary to say Yishtabach with a minyan?

• Should tefillin be put on before Yishtabach or afterwards?

• What qualities should a shaliach tzibur have?