1) What is the Islamic perspective on immunization?
2) What are the conditions governing the selection of Imaam?
3) What are the benefit or importance of Western knowledge to a Muslim and what are the disadvantage?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Answer to the first question:

There is no harm in immunization against any potential disease, as there is no difference between immunizing against a disease that could occur or treating an existing disease. It is confirmed that the Prophet said: "Whoever eats seven Madeenah dates in the morning, no poison or magic will harm him." [Al-Bukhari and Muslim] So this is evidence for preventing a harm before it takes place either by immunization or any other means. 

Answer to the second question:

If you are inquiring about the conditions for the validity of an Imaam leading the prayer, then the conditions are as follows:

1)     The Imaam should be a Muslim.

2)     He should be free from any innovation that takes the person out of the fold of Islam.

3)     He should be a male if there is one male among the people who will form the congregation.

4)      He should be in the state of ablution, either with water or Tayammum (dry ablution). Imaam An-Nawawi said: 'The Muslim nation agreed in a consensus that it is forbidden to pray behind an Imaam who has not performed ablution.'

5)     He should be a sound and sane person who is able to perform the pillars of the prayer.

6)     He should be able to recite Al-Faatihah (the opening chapter of the Quran) and have knowledge of other things that are needed to make the prayer valid.

However, if you are inquiring about the person who is more appropriate to be as an Imaam, then it is the one who memorizes the Quran more, knows all the necessary things that one should know about the rulings of the prayer as the Prophet said: "The one who should lead the prayer is the one who memorizes the Quran more than others [and reads better than them while adhering to all the rules of recitation]." [Muslim] Moreover, he should know what one should know about the ruling regarding his prayer. So if such a person exists, then he should have priority over others provided he is not a dissolute person; in such case other people are given priority who memorize less than him and recite the Quran in a way that is not as good as he does.

Answer to third question:

As for the importance of Western knowledge refer to Fataawa: 86231 and 82495.

Allaah Knows best.