The first lighting kit I bought was an ARRI kit with 750W flood, 650W fresnel, 2x 300W fresnel, and a Chimera softbox. The kit was expensive, but I could immediately realize virtually all of the textbook lighting setups (on a small scale). If you aim to light your scenes using battery power, LEDs cannot be beat. But if you are looking to learn the craft of lighting, the LEDs that are useful for that (ARRI L5-DT, etc) are quite expensive even if they are wonderfully efficient.
I have since transitioned to Joker Bug and ARRI L7-C instruments, but am glad I started with the ARRI hot light kit.
GoPro has a characteristic barrel distortion that we all recognize. It has become the signature of POV recording. If you want your B-roll to have that "shot in the first person" look of a GoPro, go for it. If you want your B-roll to give you establishing shots that look, well, solid and established, use a more sober lens and either a tripod or a slider.
For film-level resolution, the GH4. For film-level dynamic range and a real chance to get your feet wet grading footage, the Blackmagic Cinema Camera (regular, not pocket, version). In both cases, you will quickly discover that once you have your imaging platform sorted, lenses and lighting are super-important.
If you want to shoot a movie, chances are you are going to need a lens that has a nice, long, smooth focus throw, without too much breathing. Which basically rules out all AF DSLR glass, which tend to have short focus throws that can really only be dialed in by microstepper motors controlled by AF circuitry. Not to worry--there's an incredible range of affordable cine-friendly manual-focus choices these days (SLR Magic, Rokinon, etc).
And of course there's lighting--not the kind that get just enough photons on the sensor that you can check focus, but lighting that allows you to define your subject against the background, giving your scenes definition, depth, and life. You can spend tens of thousands of dollars on a really fine camera (RED EPIC DRAGON, for example) and tens of thousands more on really fine lenses (ARRI Master Primes, for example), and if you don't light your scene, you might as well use the video camera built into your smartphone.
I wrote a typo above. I meant to say "red on red", not "red one red".
A full CTB is more like 2 stops of light loss, not 2/3rds of a stop.
The color temperature of "blood red" is approx 1000K. The color temperature of a blue cyc is beyond 12000K. If you illuminate a blue cyc with tungsten, you are going to get a much darker blue than if you illuminate with HMI. Similarly, if you illuminate a red cyc with tungsten you are going to get a much brighter red than if you illuminate with HMI.
Yes, blue channel starvation is a problem with underexposed footage in RED cameras. But if you light up a red cyc with Tungsten, you are getting red one red brightness from your cyc, which is going to overexpose, or cause you to underexpose your subjects, which is going to lead to blue channel starvation.