you can reclassify both rasters and sum them.
Reclassify Urban to 1 and others to 0.
Same for the 2nd layer. High flood 1, others 0.
So if you sum rasters the area under 2 value will be both urban and high flood.
For the 2nd question, you reclassify the second layer High flood 1, others NoData.
Then Mask the 1st layer to the 2nd and only areas ...