I have no experience of the D3400, and can only learn from reading about it what you can learn by doing the same. I have owned a D3300, for years, and had no problems with it, and have found it to be a great camera....for it's type. If money is a concern, consider getting a used / refurbished D3300. If you can afford a bit more money, try a used / refurbed Nikon D7200 which has more features / capabilities which the D3300 does not. Between the D3300, and D3400, I'd go with the D3300. It has an external mike jack, and sensor cleaning, which the D3400 does not. It costs less, too.
I get to a movie theater once, or twice, every five years, if that. I stream Netflix, Hulu, Britbox, Acorn, etc, via my Roku equipped HDTV. Acorn costs $4.99 per month. I see what I want when I want, without: high movie prices, high snack prices, having to deal with other people's cell phones, having to deal with other people's conversations, having to listen to screaming children, etc. I get the best of movies / Tv shows....old, and new, foreign and domestic. Beyond that, I buy movies / Tv shows on disc. I don't generally watch broadcast TV, or go to movie theaters, since most modern domestic fare is such rubbish.
If all else fails, go to nikonusa.com, online, and inquire there.
Melbourne, Australia....a great place to be. Did you visit Dracula's Cabaret? Did you see the VCR sized 'Welcome Stranger' gold nugget ( 66kg) ? Did you get to Moomba? I have been to Melbourne, and am anxious to return. The place is full of great photo ops...as you have proven.
Basically, performers own a Copyright on their images...of their faces, instruments, etc. If they do not defend that Copyright-if they let anyone, and everyone photograph them-they lose the copyright. Then, they won't get paid big money to be photographed by pros to endorse: food, candy, beer, clothes, cars, etc.
Who the F wants to shoot photos at concerts? Over lit images of the backs of the heads of the people in front of you? Tiny, under lit, images of distant performers who can't be recognized? What is the point? If I wanted concert photos, I would take my Press Pass, and arrange to get on stage / back stage access, and permission over which no ban would have power.
Stay inside, and watch the eclipse on a TV news broadcast...cheap, and safe.
Canon cameras all have Anti-Aliasing filters...OLPFs. That makes every shot a bit blurry. One more reason to own Nikon.
A second sun would create more, and harsher, shadows. More clouds would soften shadows.
It depends upon the lighting, your distance from the things photographed, etc. Personally, I'd use a Nikon, for the greater Dynamic Range. Rent a Nikon D810, and a 35mm Prime lens. Shoot the same scenes, actors, etc, with all of the Canon gear, and with the Nikon gear. Compare the images from both later on. The 35mm lens will get you a lot of image, which you can keep, or crop, as you please later. The Prime lens image will be better than any Zoom lens image. Consider getting a Press Pass, and shooting for the local newspaper. Then you can get up front, on stage, and backstage.
Supposedly, all will be revealed in full on 8-16-17. I will wait until then to investigate it much. Rumors have swirled about the camera for over a year, and most will probably be wrong. Only the name seems really certain at this point. The D850 will, undoubtedly, cost a bit...but will probably be worth it. I will wait awhile, save up a bit, and buy one before my next trip abroad. The D810 was a great camera, and the D850 is apt to be better still. I will get the full details before actually laying down money for it, but I currently have high expectations.
And Garth Brooks is-once again....for the 5th, or 6th, time...cutting his last ever record, going on his last ever tour, and then retiring from the life forever. Sure. Most of what T.A.P. says seems to be useful enough, but his manner of saying it is sometimes annoying. I occasionally view his stuff, but he is never the first source I check on anything. He does have a nice lens collection.
I have one, as well as a Canon A-1, a Pentax 67, a Nikon N8008S, a Mamiya RB-67 Pro, and a Mamiya C-330...all the film systems I need. Try advertising the K-1000 for sale, online, or donate it to a local camera club.
The plug adaptor alone should work fine. It did for me in Australia.