Ok there's what the label says, and what I have experienced myself: the label says it's permanent if you use a 20vol developer or higher, and they recommend 20vol for gray coverage. The demi and semi permanent results are, according to the package, achieved when using less powerful developers and/or less development time. Now, for what I have personally experienced and I've been using the product exclusively for a year: I was once upon a time a redhead which ended up an l5 brown and is now 50white with gray and see awful blackish coarse stuff too, and I have a horrible time getting adequate root coverage, color that doesn't lift hot on my grays, and damage and porosity. For me, I find 20vol makes my hair too coarse and orangey, and 10vol doesn't get the cuticle open enough to cover my whites. I mix 10vol and 20vol to get just the right amount of lift. Now, why this brand? I find the smell to be very pleasant, the colors rich natural and long lasting, fading to nice natural tones, and minimal.damage to my hair, even as I extend the development time to 45 minutes when working with copper tones. I also found the gray coverage series helpful, I use it as a 'base tone' (50 percent of total.color in each batch) and a couple of other colors of similar level, to get the exact time I'm looking for. I have found that no color is truly 'permanent', it's merely a question of how soon it fades and what it fades to. To directly answer your question of comparing to the Ion color brand , I find the Chi Ionic smells better, is less harsh, and has more natural looking colors. Please note that I don't use any of the intense colors, I strictly use only browns, coppers, and golden and natural blonde so I can't vouch for any of the rest. What else... Oh yeah,there's a recipe for adding in the color conditioner, I didn't really like that product more did I feel that it did anything other than dilute my color. Good luck!

I wrote a much longer answer before. Here's a short answer: 50 series 8WG 2Ovol at roots only, then the rest of the hair 9WG regular series with 10vol, develop at least 45 min, with cap and hair dryer on low if the roots need a nudge grabbing the color.

No, you need to bleach then apply color

2

This particular color works best with 20 volume developer "Chi Generator" which will only lift hair about 2 shades/levels lighter than your current hair color.  It may turn your hair orange, especially if you try using it with a higher number of developer such as 40 volume. The only way to know for sure is to test this on a small section of your hair about a 1/4" width and see what happens.  

Yes. One colour to one developer for Demi permanent, one color to two developer for permanent color. 

Mixing & Timing Permanent - Standard Series: Mix 1:1 with 10, 20, 30 or 40 Volume Color Generator and process for up to 30 minutes normal. Low heat timing can be used when lifting. - Natural Gray Coverage: Mix 1:1 with 20 Volume Color Generator and process for 30 minutes normal/45 minutes resistant, or with low heat for 10 minutes and 10 minutes room temperature. Demi Permanent - Mix 1:1:1 - 1 Color, 1 10 Volume Color Generator, 1 Clear and process at room temperature for up to 30 minutes normal. Semi-Permanent - Conditioning Glaze Formula: Mix 1:1:1 - 1 Color, 1 10 Volume Color Generator, 1 Color Lock and process at room temperature for up to 10 minutes normal.