Leave the roots...dangling roots are a wonderful source of food for small fish, which is why you see fish in among roots so often. Once the Wisteria gets growing, roots will grow from every node along the stems, along with leaves.
On the Java Fern adventitious (= daughter) plants, I would leave them until the fronds (leaves) are much more substantial, along with the hair-like roots. This might end up being weeks if not months. These are the plants that do well in wood crevices when planted. They can also be left floating. In their natural habitat, these adventitious plants break off and float to their new "home."
If you want to spend money on the pruning set, fine, but I have never had one in my 20 years of planted tanks. I do have a pair of scissors that I have used from the start exclusively in the fish tanks. These are useful with tough plants like Java Fern if you want to remove a yellowing dying leaf. But for most all other plants, I use my fingers. You can go through most stems fairly easily with your thumb nail and forefinger.
Byron.