[G.R.Morrison]

The (inverted) gull wing allowed the landing gear to be shorter, sturdier. Most Luftwaffe types were able to operate from unimproved airfields. A retractable undercarriage mechanism adds weight and complication, which means toting less ordnance or fuel - all designs are a trade-off. Observe how many nations' aircraft from the 1930s had fixed undercarriage, and how few had retractable.

All the Stuka fliers knew they had the slowest airplane at the front, but it didn't matter. It was intended to be 'flying artillery,' and it was the job of the Bf 109s to take care of interference. The Stuka was quite maneuverable. Look for Eric "Winkle" Brown's assessment (he flew a remarkable variety -- check Wiki for the list).

You may wish to track down the recently-republished English translation of Helmut Mahlke's memoirs (he flew in the Trägergruppe, and later led the III/St.G. 1) for an early-war personal account.

GRM