You might find a rear Ultegra mid-cage DR and cassette a less expensive change than a crankset change. Or a 105 mid-cage DR will be even less. Are you certain that DR is a SS version and not a GS version?
As for changing the small chain ring, someone else will have to say. Even if the small 34 will fit a big 52, that's a lot of difference and you'll be out of the min/max diff for the DR, as well as other spec's.