Is my redundancy identification and K-Map grouping correct?
To use k-map you must consider all the rules.
What you miss is the rule saying that you should have as few groups as possible.
So after covering all 1s you should not add additional groups just because they can fit.
In problem 7, the group (m2,m6) is just one additional group that you do not need. To get the boolean expression of  (m0,m2) for example,  you omit the boolean variable that does not keep its state inside the group which is Y so (m0,m2) is represented by X'Z' and the whole simplified expression will be: X'Z' + XY.
In problem 8, groups (0,1,3,2) , (4,5,12,13) and (15,14,11,10) are enough. But this is not the only solution and your choice is valid. While enumerating all groups you missed (3,2,11,10).