Non-Muslim donating money towards the building of a Musjid

Q:

1) If a non-muslim ( hindu or christian, etc ) gives money towards the building of a mosque, is it acceptable?

2) If the whole project of building a mosque has been financed by a non-muslim, can we pray in such a mosque? Will our prayers be acceptable?

3) If a non-muslim has financed the building of a madrasah, or some classes of that madrasah, is that acceptable? Can our children learn there?

Corrupt beliefs

Q: One 'scholar' mentioned that the Qur'an states:

"Were it not the case that people stood up for each other and defended each other, then temples, synagogues, churches and mosques would be destroyed as a result of tyranny." He then goes on to say: "And it's very interesting that in the same verse places of worship of different religions are mentioned by God to demonstrate it is God's design to have all these religions." Furthermore he states: "The Middle East is the cradle of Christianity. For many years I have lamented the emptying of these lands of its Christian populations. The former Archbishop Lord Williams, with our current Archbishop, with my dear friend and brother His Grace Bishop Angelos & many other Christian leaders, I have lamented this fact that the Middle East is poorer without its Christian population." "Christianity was there first. Islam came later. Muslims came later and they lived together for centuries peacefully."

I wanted to ask 2 questions: (1) Is what he said correct? (2) If not, which bits are incorrect and why?

Dajjaal

Q:

1. What work will shaytaan do after the appearence of dajjal?

2. Will dajjaal be sent to hell or he will be destroyed after qiyamaah?

3. Was dajjaal created for the specific reason of testing Muslims or he was punished with this activity?

Doubts with regards to mistakes in Salaah

Q: I have constant waswas.

1. When I am reciting suras in salah or reciting tashahud sometimes the letters do not come out loud enough so I can hear. Is my Salaah still valid?

2. If I make a mistake in reciting in Salah how far do I go back to correct myself. Do I restart from one whole verse or just from where I made the mistake.

3. In tashahud I didn't say "warahmatullah hi barakatu" properly, so I went back to that bit and recited it again. Is the salaah valid?