What was the layout of bathhouses in earlier times?

Bathhouses used to be comprised of three rooms. An inner room contained the actual bath. In this room people were unclothed, and it was forbidden to wear tefillin there or to be involved in any other matters of kedusha. The middle room served as a changing station. People in this area were in various states of undress. In this room, too, it was forbidden to put on tefillin or to be engaged in devarim shebekedusha. One who was already wearing tefillin before he walked in could continue to wear them. The outer room, where people were fully dressed, had no restrictions.

סימן מו, ס"ק א; ביאורים ומוספים דרשו, 2

What is the nature of Birchos Hashachar?

Chazal instituted that a person should recite the Birchos Hashachar every morning. These brochos focus on the various spiritual and physical enjoyments which a person experiences throughout the day. Some Rishonim classify these brochos as birchos hanehenin--brochos which one recites before enjoying a pleasure of this world. Having enjoyment without making a brocha is akin to stealing. Other Rishonim explain that Birchos Hashachar are brochos of praise, extolling Hakodosh Boruch Hu for the qualities of the world that He created and sustains. 

סימן מו, ס"ק א; ביאורים ומוספים דרשו, 2

What is the guarantee for one who recites Adon Olam?

Prior to walking into a beis hakneses, a person should recite the pasuk of V’ani B’rov Chasdecha. This pasuk is a form of requesting permission to enter the shul and daven to Hashem. There is also a custom to say the piyut of Adon Olam. Some Achronim explain that Avrohom Avinu--who instituted the tefilah of Shacharis--was the first one to refer to Hashem as Adon Olam (Master of the world). It is quoted from earlier sources that one who recites Adon Olam with proper kavanah is guaranteed that his tefillah will be heard without interference from the Soton.

סימן מו, הקדמת המשנ"ב; ביאורים ומוספים דרשו, 1

• It is forbidden to take a nap while wearing either the shel yad or shel rosh. If one sees another person sleeping while wearing tefillin, he must awaken him.

• It is forbidden to be masiach da’as (lose focus) from the tefillin while they are being worn. The poskim explain that hesech hada’as occurs when one acts with levity and lightheadedness.

• It is forbidden to wear tefillin within four amos or less of a dead body or grave. Doing so mocks the deceased, who can no longer keep mitzvos.

• Who instituted the recitation of meah brochos?

• How does one reach one hundred daily brochos?

• What are alternative ways to reach one hundred brochos?