I find your first premise the easiest to believe but why would anyone with half a brain vote for any Democrat believing they would be more fiscally restrained. It would be total stupidity.
Because they believed the Democrat campaign promises. The biggest group to move democrat was voters who turned 18 since Bush assumed office and thus do not remember the tax increases that accompanied the start of the Clinton presidency. These voters also do not remember the excesses that led to the repudiation of Dem politics in 1980 or 1994. The press will not acknowledge the degree to which Dems were repudiated in 1980.
It hurt republicans at all levels that Bush has seemed to be determined to repudiate all aspects of the Republican brand upon which Republicans ran on in 1994.