Don't worry, I was a little slow on the uptake too regarding the windshield... I was driving along one day and was a little irked at my kids for not washing it while filling up, and that's when it dawned on me. There are some things you just don't think of.
I haven't bought one yet, but the OBD adapters aren't too much according to posts I've seen on the Internet, like $20 - $50. It appears, like anything, that some are better than others, so it is worth researching. I don't have the app either since I don't have an Android; hence my looking around. I didn't know about the app not working on 2015. Interesting... I saw a post that this last July Nissan has blocked third party apps from getting in to some internal settings in the car; I'm not sure if or how it affected the Leaf Spy app. Some settings are more for review (battery condition, battery temperature, etc) while others affect the car's performance, apparently. Again, I'm on the learning curve here.
I'd be surprised if you don't have an 80% setting; but I know ours is kind of buried in the various menus. Based on your first post, it sounds like you would do well with just an 80%, and based on that video it would do your car really well too. So it's worth checking into. Of course the first few weeks we suffered from KWH anxiety, which I think is a pretty normal feeling, but like any other tool, we have become pretty comfortable with knowing our boundaries. We are in the Carson City Nevada area, so there aren't a ton of public charging stations, but there are a few. Oh, BTW, those public charging stations (so far) are free. Sign up for the ChargePoint (or whatever it's called), swipe the card they send you, and you get free fill-ups. Even if it did cost, the going rate per mile of one fourth the cost of gasoline (or less). I made a little Excel calculator; if interested let me know.
I bought a Clipper Creek HCS-40 level 2 unit. The actual charger itself is built into the Leaf, I have a 6.6KW on mine, so this is more properly termed a controller. The car talks to the controller and when the car is done it tells the controller to shut off. I'm also happy with this Clipper Creek unit; very quiet, no bells and whistles, much smaller than some others on the market. Altogether, including shipping, it set me back $624.06. I've heard that, starting just a month or so ago, that Nissan is giving new customers a level 2 unit with the car. That would be nice...