Mixing purples??

You are going to get a dark purple over a darker base. If you want a brighter shade you need a blonde base.
Diluting the dye prior to application (especially with heavily pigmented dyes like SFX) and shampooing out any excess dye will help to stop any bleeding. Rinsing in cold water and vinegar rinses help to seal it in too.
How long it will last for depends on the porosity of your hair and how long you have left the dye on for, as well as how you maintain it. All hair dyes can stain so it may never fully wash out. Leaving the dye on longer tends to make it last longer rather than making the colour darker.

Thanks, so will I get this sort of purple over my base colour

No. Maybe closer to the top one, but as your strand tests have shown you can either have a dark purple or a very pinky purple over an auburn base. Those pics are photoshopped, but the only way to get a vivid or light purple is to apply to a fully bleached base.

They both require a lighter base than yours. Have a look at the unbleached hair section of the beeunique hair dye gallery to see what kind of colours dyes will show up over darker hair.

For a purple that shade you would need a more blonde base. A magenta, red or pink based dark purple would work over your hair.

Edit: beaten to it 🙂

Ok thanks, one last thing, what kind of fade would I get from a adore violet gem?, and the sfx pimpin purple?  I've also just mixed the violet gem with a neon blue and that's come up as nice purple too soo what kind of fade would that be??  I'm tempted to use all three to give different purple shades any tips on best way to do this ?

Most purples will fade more red/burgundy on that type of base. The bluer the purple the browner it will fade. Pimpin Purple definitely fades very pink, I would expect Violet Gem to as well.

Here it is using sfx pimpin purple

Here's a better one a bit patchy in places but all good 😃

It looks cute 🙂