John converts $100,000 regular IRA to Roth prior to 12/31/98. If 4 year spread is selected would put $25,000 in each year for 1998,1999,2000 & 2001.
Question: Can John use a spread less than 4 years? Ex: 1998: $25,000, 1999: $25,000, 2000: $50,000.
Question: What happens if John dies prior to year 2000? Does the estate have to pay taxes on remaining $50,000?

If the four year spread is used, then it's four years, equal reporting of income (unless a withdrawal is taken, but that's a different story).

If the taxpayer dies and the spouse does not inherit the Roth, then the remaining income is reported for the year of death.