One can sleep with Tefillin under his head- the bulge of the Tefillin should not be directly under his dead though. Other Amoraim followed similar methods of wrapping their Tefiillin in double wrappings near their bed to keep them safe.

Two naked people lying under a blanket. Face to face it is surely forbidden to recite the Shema. But buttock to buttock there is a dispute. One opinion permits his wife (his wife is like "his own body" but forbids anyone else and one opinion allows both someone else and his wife. The root of the question is whether the buttocks area is called "ervah." Another scenario where this is relevant is a naked woman making a bracha sitting on the ground.

Little children's private areas do not present issue of ervah. What is the age that it becomes ervah? One opinion says 3 for girl and 9 for a boy. Another opinion says 11 for a girl and 12 for a boy.

Exposed pubic hair is not evan.

To gaze any part of forbidden woman for pleasure is forbidden. To be in line of vision without gazing for pleasure it is only an issue is there is one teach of usually covered area that is exposed and then one cannot say Shema within that line of vision.

Thigh is ervah. Voice is ervah. Hair is ervah.

One should not hand tefiilin TEfiilin by their straps. It is a dispute if they can be hung by their boxes. It's definitely ok to hand them from their bag, but a Sefer Torah should not never be hung in any of these ways

One should not pray out loud. IF they need it to help concentrate it is ok but not if it disturbs other people praying.

Belching and yawning during Shmone esrei is wrong if done voluntarily but fine is happens involuntarily

Sneezing from nose is totally fine and actually a good sign. Passing wind is not good and is a bad sign.

One should not spit during davening but should rather absorb it in his cloak. If that is disgusting to him, he should spit it backwards.

For someone who can't control passing wind during davening they should move back 4 amos pass wind and then there is a special prayer recited before resuming davening

A naked person under blanket cannot say Shema unless they block the head from the ervah. Others require the heart to be blocked from the ervah as well.

One cannot think Torah is dirty alley, but there is a dispute if one can think or recite Shema while walking through the alley if they don't stop there.