1. Many many did. Many got bailed out by you and me.
2. The government didn't force them. The banks tried to recoup as much money as possible after being forced to make bad loans. They bundled all that worthless paper together and said to another bank, "hey pal, I got all these mortgages for sale, worth billions, but since I like you I'll give it to you cheap." This happened over and over again until there was no one left to buy the worthless paper. Pop goes the bubble.
3. Wrong, the banks moved into sub-prime loans BECAUSE the government forced/pushed them to through threat of racism, big vs. little guy, etc. Janet Reno employed strong arm tactics to achieve this. Threats of investigation, etc. She was the Eric Holder of the time remember.
4. They haven't. That's a media false narrative they would love for you to believe. Again, what money lender wants to give money away, I ask you?? It doesn't make logical sense to make a loan that you lose money on, does it?