Are Invented Enhancements better than SO or DO enhancements?
Generally better.
Do Invented Enhancements have level ranges like SO and DO's?
Yes, and no. Invented enhancements have levels, but that just affects when you can slot them, the actual buff they give doesn't change - they always give the same buff regardless of your level. e.g. a L10 IO will always give you the same buff whether you're L7 or L50.
That goes both ways, you can't get an extra buff by slotting enhancements three levels above you like with SOs, but they also don't expire when they're 4 levels below you.
Slotting +3 SOs will give you a better buff than the same level IO up to a point (L30 ish I think), but it's a lot more expensive because you need to replace the SOs whenever you level. So I'd personally go with IOs right from the start.
Once you gain a Recipie does that mean you can make as many of an item as you want (as long as you have the salvage required obviously)...
No, recipes are used up. But if you build enough of various types you get the crafting badge which lets you have the recipes memorized, so at that point you don't need the recipes.
I assume i can keep recipies that i wont use personally so that i can sell the products to other players... If thats the case they must have implemented some sort of Auction House.
Yes, the consignment house, there's one in atlas, king's row, steel, talos...
You'll find enhancements tend to sell for less than their actual crafting cost at the moment, because of all the people making them for badges meaning there's more supply than demand. You can also sell recipes and salvage at the usual shops, and some particularly common and undemanded stuff goes for more there than at the consignment house.
