There are over 10 different models/combo kits to choose from, but if you are specifically referring to the 3-in-1 models: 1. Model# SXL31, on the surface, appears to be just a newer version of the SL31, but thes SXL31 allows a max 2.5 inch fastener, 2. Model# SL31, allows a maximum of 2.0 inch fastener.
I don't see why not. Get familiar with its operation first and use some scrap to set your depth or you could leave pick marks on your finished surface.
Yes, you can nail through the top of the first row of flooring against the wall where the hole will be covered up by trim. Second and third rows, if necessary, would be a little more difficult because you will need to nail into the correct spot in the tongue of the flooring, at the correct angle, most likely with the 18ga narrow crown staples. Refer to the flooring manufacturers installation instructions before doing any nailing to make sure you don't void their warranty by using the incorrect fastener.
No case for the one I bought. Oil-free? Sure! As long as you plan to replace it sooner than later.
At Home Depot, of course!