Both should be possible, however, it is not common to find subsoiler equipment for smaller equipment. You might be able to find a plug roller or other aeration device that could be pulled behind a lawntractor that will give similar types of benefits as far as aeration and water penetration. Digging retention ponds as high on the property as possible mas also be difficult in smaller lot sizes if one thinks in terms of bulldozers, but water retention can have many faces as well. Swales to move water around the property can also be seen in light of fitting the property.
Bottom line is that a small retention pond built with a shovel and pick axe is still better than none.
Hope this helps you think through how to start getting the benefits without getting bogged down with big budget/equipment problems.
More details on your lot/plot size might help others give you pointed suggestions and ideas.
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