Wa `alaykum as-salamu wa rahmatullahi wa barakatuh

Let me answer your question in their respective order:

1- Tayammum is a symbolic substitute when we cannot use water for ablutions: Allah says in the Quran:

“O you who believe! When you are about to pray, wash your face, and your hands and arms up to the elbows, and pass your [wet] hands lightly over your head, and [wash] your feet up to the ankles. And if you are in a state. requiring total ablution, purify yourselves.  But if you are ill, or are travelling, or have just satisfied a want of nature, or have cohabited with a woman, and can find no water-then take resort to pure dust, passing therewith lightly over your face and your hands. God does not want to impose any hardship on you, but wants to make you pure, and to bestow upon you the full measure of His blessings, so that you might have cause to be grateful.” (Al-Ma`idah 5:6)

We can infer the following from the above verse:

1- We are to use water for purification – unless we are prevented from using it because of ill-health, unavailability of water, etc.

2- In the latter case, we are to perform tayammum or symbolic ablution.

3- Tayammum entails striking the earth with both hands once and then wiping  over face and hands once (after blowing away any dust sticking to the hands before wiping)

The Prophet (peace be upon him) told `Ammar b. Yasir who rolled over the mud: “It would have been enough for you to strike (a clean) ground once with your hands and then wipe your face and hands with it.”

In another narration, we are told that the Prophet ordered to blow away any dust sticking on the hands before wiping the face and hands.

It is clear from the above that the intent of tayammum is not to smear our hands and face with dust. Rather, it is merely a symbolic substitute to reinforce the idea of ablution as a prerequisite before standing up for prayer.

Now the question arises how could one perform tayammum in the hospital: The answer is: Ideally, one should get a few grains of sand or clean dry earth or a rock piece to strike on and perform tayammum. In case nothing of the above is available, then he or she may strike on the bed or wall and perform tayammum as mentioned above. Allah says: “Fear Allah as best as you can.” (At-Taghabun 64:16)

2- There is no objection in addressing religious officials of other religions by their official titles: We know that the Prophet referred to the religious officials of Jews and Christians by their titles.

By doing so, we are simply observing the proper etiquette of conversations; it does not in any way involve compromising our own religious identity or principles. Even as we expect them to address our religious officials such as imams or shaikhs by their titles, we should reciprocate the same.

Finally, it is important to point out that Islam encouraged civility and observance of acceptable social decorum in social interactions.

Almighty Allah knows best.