1. Normally you re-use the drop pipe. Would that apply?
2. If you have steel casing the recommendation would differ than if you have PVC casing. With steel, I would be looking to an SQ pump.
3. a 1 HP 20gpm pump is way overkill for a house, but would be ok if doing a lot of higher volume irrigation.
4. If irrigating your farm for hours on end, you will want a more power-efficient pump.