Hi Wendy,
DoF will be tight, it is to be expected when going this small.
These are all Auto Focused, so no hassle there, just snap a few and pick the sharpest, practice makes you better at choosing which bit to put the focus point on.
I am thinking the bugs are getting a bit repetitive, so perhaps I'll try a flower or two, sorry, in our garden; a weed or two.
Expected sharpness? Well, as you say, it is no sharper than the other one really.
Ease of Use; I have died and gone to heaven! AF works 90% of time and exposure is also right most of time, the result is I miss far, far, far less shots with this AF-S macro lens than I did with the manual AI (on D5000).
Cheers,