Exempt Interest on mutual funds are tax free, but would AMT affect all shareholders?

Does Alternative Minimum Tax change from one individual to other or is it a rate applicable all? How is AMT determined?
Would municipal bond funds decalre exempt interest or reallocate income dividend to exempt intest?
What is foreign tax paid in the Form 1099-INT?

Exempt interest mutual funds yield exempt interest and there can be short term cap gain and long term cap gain. The interest is exempt from federal tax and depending on your state law could be exexpt fully in your state or taxable in your state to the extent of interest received on other state bond. The cap gains will be taxable federal, but there generally is not must gain on a fund.
The almin tax rate is either 26 or 28% depending on your income level. Exempt interest can be subject to alt min in the fund ivests in state bonds that are subject to alt min, again there usually is not much of this.
Foreign tax paid on a 1099-INT foreign tax withheld on a foreign bond that paid interest. This tax can be taken as a foreign tax credit on your federal tax return.

The rate of income that is subject to AMT is the same for all shareholders (because all shareholders own a proportionate share of the fund). In a mutual fund, this arises because of what are called "Private Activity Bonds" - municipal bonds that are for private works. Although, the income may be subject to AMT it does not mean that you will actually suffer it. All taxable income is subject to AMT if you meet the conditions and, as you have seen, some tax-free income is too.

Municipal bond funds must pass through the income in the same manner as it arrives to them. They cannot re-allocate it. So if a fund invests in, say, US Treasury Bonds, you will have a 1099 for that part of the income and will pay tax on it. The municipal bond income will remain free of federal taxation.