google nikon center, i never hear about repairing coating, i guess maybe they just change element for that. 

just shoot auto and concentrate on composition first.
then play with the rest once u know what u want to achieve, else everything is pointless.

In my opinion, the best way to learn is getting out there and shoot you can learn the basics of exposure on a lot of websites, I remember that I was shooting a running fan to know the basics of shutter speed and ISO

Aiks... Pricey. How you know? 
Reading is one thing. Experimenting is another. They go hand in hand. Therefore go out and shoot. 

I usually don't use any UV filters on my lenses ! If I use CPL, that would be on my wide angle. For that, I use the Fotodiox Wonderpana special mount and a fairly large CPL (145mm) that does not give uneven polarisation. I use the Wonderpana mount more for mounting graduated ND filters.
Something to confess... I've actually only learned to use the BBF recently like 3 or 4 years ago even though I read about the merits of BBF. Before this I've always used the half press shutter button to focus. Unlinking the focus and shutter release actually makes sense. After many years, it took a while to kick the old habit and relearn how to shoot using the BBF technique.

But just a tip... If your camera is already set up to use the BBF, be careful if you hand over your camera to somebody else to take a pic of you for some reason... They might just use the shutter button to shoot a pic and give you an unfocused pic.

Shutter is always the minimum amount you need to get a steady shot.

ISO used is always the minimum amount that allows you to get the shutter speed and aperture.

Nailing the shot is more important than noise. Noise will not fail a photo unless it's too severe or the photo has a certain purpose like commercial work, even so commercial work still can tolerate certain level of noise because it very much depends on the size of the image and what kind of application.

I've had ISO 800 - 1600 photos from my EOS 350D printed to 9ft x 4ft and plasters all over buildings before, no issue despite the noise and all. Why?

1. viewing distance
2. print quality

Understandable, you're using a D3200. As long as under 1600 it'll be alright.