Given that bad thoughts about another person created in the dream state can actually harm them energetically, and incur a karmic penalty, how often do positive dreams with happy, loving, thoughts about another person create a benefit for that target, or do we spend most of our dream time focused on the negative?

This can certainly take place, that a positive dream, thoughts of love, appreciation, and gratitude about another person constitute an act of loving kindness that will attach to their akashic records as a kind of blessing and will be noted by the Law of Karma and brought into their life experience at some point, seeking a home for the creative impulse to impinge on the universe. That is your role as divine human, to be a creator in your own right, so everything you do will have some influence, however minor, on the universe at large. The more focused and targeted your thoughts and feelings are, the more likely they are to change something for the better, or worse, as the case may be. What governs the nature of the dream state is the makeup of the individual and the current life experience they undergo. The primary function of the dream process itself, is to go through the day’s events to review them, with that review serving to assign importance and priority to some things more than others, and assist in the process of memory consolidation so those things useful to recall later on can be stored in long-term memory for safekeeping, while much trivia is dispensed with as unimportant. This is why people remember the big events in their lives but not the humdrum of the ordinary day-to-day sameness they will experience at times, but which leaves relatively little impact, at least in terms of affecting the future. It is those things stored away and the energy associated through the power of the intention launching them forth, which acts as a springboard for the Law of Karma to return to their creator a consequence of some kind. That will be good or bad, if the intentions of the original thoughts are positive or negative, respectively. So you are able to ameliorate the slings and arrows of life to some degree, even when processing the events of the day. But you will make them worse and have greater impact if you agonize over them, take them to heart, are triggered greatly by having had prior trauma of a similar kind, and so on. This is simply how life unfolds. As a participant in it, you will influence the course of events directly as well as indirectly, through these kinds of mechanisms. On average, we would say people are more negative than positive, so for many individuals the vast majority of their dreamtime is much like a battle zone where they are reeling from challenges and the onslaught of criticism and negativity they must cope with. That is most unfortunate, because it diverts much useful spiritual capital into a kind of holding action at best, and rarely effective healing. That, the mind at a deep level is not able to perform very effectively. It must reckon with danger and threats to the being of all kinds, big and small, because that is its job. So if you want a happy-go-lucky, carefree existence, don't expect your mind to cooperate with you because it will be looking for trouble and will likely find it, at least some of the time, given the nature of the world you inhabit, and for some it will be a full-time endeavor.