Can I create and save presets?

It depends on what you mean by a preset. The notion of a preset in the popular sense does not exist in Har-Bal and for good reason.

We have found through extensive testing that while you can make a one button preset work with some success the results obtainable are far from optimal and usually far worse than what you could obtain through custom adjustment of Har-Bal. As such we have deliberately left out a filter level preset until such time as we can come up with a mechanism that will work satisfactorily at least 95% of the time.
The fact is that because of the way the user interface is structured it is generally very easy to construct as satisfactory EQ filter for a given track so lacking a filter preset is not much of a penalty.