There is no need to change the crankset. The original BCD 130 crankset allow the mounting of a compact 50-34t chainring

For the rear hub, its a standard 135mm OLD rear hub, so any standard rear hub with a Shimano body will fit. Depending of the freewheel type of the hub you will buy, you may need some spacers to mount a 8s cassette.

Personally, I do not like a 11-32 8s cassette because the gaps between the gears is too big. A 10s Deore like mounted on the Birdy Touring is better. Matching cassettes exists in 11-32, 11-34 and 11-36t.