Noob question getting more traffic

Ok so I have a youtube channel. I wondering about a few things perhaps use lot can answer. I have watched videos and read forms and a bit confused.

1. I have done some key word research picking medium long a short keywords. Also checking what keywords the top people in my niche use. Trying to see what they doing.

2. When picking my words I just think what would I type if I was looking for my video, check that phrase or word if it's to high leave it check another I have about 16 that are medium so I use them on all my videos should I change them round.

My first question is when tagging my video there 500 characters allowed should I use all 500. I've noticed some say yes some say no.

Second question when doing my description I do a description in detail for humans to read then my social links and a block of text containing long short key words is this a good or bad idea.

3rd question when I upload the video to youtube does it matter what the file was named on my desktop I've read it does and other places that it dosent.

Also if any of you any tips on improving views please feel free to share. I've decent enough traffic considering I only starting out. These just a few things I was wondering...

My opinion!
You might consider using all 500 chars, but imagine you typing on your phone for a vid and pressing enter.. Have you looked at what you've typed? is it the correct name or w/e you were looking for or are there typo's.. ? You might want to consider adding some typo's in your keywords. or use a few long tailed keyword

thanks mate that is actually really clever like buisness and business people always get them wrong.

What is your youtube channel about? content will always be more important than keywords

I have two at the moment, one is a fail niche i make compilations an then top 10's i certain categories. Still experimenting with what gets the most views an that i not using anything like ytmonster or addmefast sites. I have built up an awful lot of credits in them to eventually use them to push couple thousand views to a video and bump it.

I just wanna get everything right before that.

My second channel is my business page i own a gym, myself and few the guys i have working being recording things the last few weeks, Sssshh they don't know i plan to make money they think it just going on the website. i building the gym's social network up totally organic and natural i know them video's will get thousands of views when shared, but would be nice to also have them tagged right and all that..

Buy some