I love your house! I absolutely love the craftsman bungalow style. My daughter & son-in-law just bought one almost identical to it, except theirs is not brick. Their attic is finished, though the previous owners did not use the best of workmanship. The finished attic adds about 450 square feet to a house whose main level is 936 sf.
You can certainly finish your attic, though you really need to sit down and figure out whether it's worth the cost. Heating and cooling will be a big issue, and (based on seeing old wiring) you'll need to update your electrical. Check all local codes, and try to estimate what the improvement will do to your property taxes. Most contractors are going to be "less than thrilled" with this project, due partly to the difficulty of getting materials up there. So unless you're doing a lot of the work yourself, it may be cost prohibitive.
Everything should be fine structurally, provided you don't go wild with porcelain tile or anything. These houses were designed with the assumption that the attics would be used for more than just storage. The 4' half-walls will actually stabilize your roof just a bit. Adding a half-bath might be a good option.
Let us know what you decide.