And here's some short answers for your questions.
Does the stars contribute to the +fire ect. Or is it the dc/mc stats?
No. Stats do not influence the output of the design or essence. Only
level and
quality of the item will determine the quality and level of the essence/design. (These are random by the way - you won't always receive a level 106 essence from a 106 item, equally you won't always receive an artefact design/essence from an artefact quality item)
Edit: just realised what you meant here, sorry I misread.
Typically yeah the stars are influenced by the number of magical properties on an item (such as Fire Damage +%) but also adding some Primary Stats using Gems/Orbs (such as AC/AMC/DC/SC/MC etc.
see here for more details on Primary Stats) to items can increase it's quality a couple of stars at least as well.
I salvage it and I can get one of two things...essence or design?
Yeah, the chance is random. The designs are specific to the item you are salvaging - i.e. Weapons produce weapon designs, Jewelry produces Jewelry Designs etc. These can then only be used to upgrade an item of the same type.
Does it mean that the 5 stars carry over to either one of them?
Potentially yes, but the chance is random so it won't always result in an item of the same quality. It just has a higher chance of it not being a lower quality. You can even receive the upgraded item at higher quality than 5 stars, the chance is lower that's all.
Then what? I need to find another essence or design roughly same lvl?
Roughly yeah, or higher than the item you are trying to upgrade. Say your item is level 105, you need the essence and design to be 105% purity/detail or higher.
Then upgrade what ever it is I need to upgrade with both ess & des. After that I get a red item but with no stars? ( which makes me think why I need to use high star items to salvage.?)
The resulting item from a successful upgrade using the essence and design will become
Unidentified (Red). You will need an Identification Scroll to reveal it's new stats.
Then I use a 1mil scroll to get the best stats poss? Again does a 1m scroll give you better chance of getting a higher stared item?
It won't give you higher stats - this is still determined by the amount of Slag/Fade from the essence & design. The higher quality scrolls will give you a better chance of revealing the item in it's best form relative to the stats of the design / essence used. So you can use a 1* design and essence, the scroll won't give you a better chance at Artefact quality, it will merely increase your chances of getting the best possible output from the design/essence.
So, here's an example:
You have:
Essence - [Volume: 80%] - [Purity: 105%] - [Slag: 0.70%]
Design - [Quality: 80%] - [Detail: 105%] - [Fade: 0.70%]
The resulting item (level 105 or below - Purity/Detail 105%) has a high chance of being Artefact quality (Volume/Quality 80%) with a good chance of having high stats (Fade/Slag 0.70%)
Using a low quality scroll has a higher likelyhood of revealing lower quality and lower stats. But because you used good quality design/essence, using a more expensive scroll will have a great chance of revealing the item with it's best possible qualities. The magic attributes will still be random, so don't think that just because you want Fire Damage % on your gear it will give you it. You may still get an undesired stat but it will have a good bonus % increase to it because of the slag/fade being low from the essence/design.
Sorry if I've completely ruined your brain with this post but I'm struggling to fully understand it.
Don't worry, nothing to apologise for. Every expert was once a beginner! Just remember though, you won't always receive great upgrades on your items after a couple tries at upgrading - the element of RNG is a force to be reckoned with! Like Zade says, some players have spent a lot of money and effort trying to upgrade their items. My 9.7% Lightning Damage Revival Ring took me a fair few goes before I got it how I wanted, and that's only a level 16 item, so imagine what it will be like with level 150+ items.
Beaten to it by the wonderful Warda
Thanks for saving me a ton of typing hahaha
You're welcome! Thank you for having a go though as ever Zade!