I will link two threads at the bottom of this post that are fantastic sources not only for how you should set up your vivarium but also how to care for your Leo. They are great guides for beginners and the experienced alike.
You will find things that work better for you as do many of us but the guides are the general outlines.
As for housing two Leo's, yes having two females will reduce fighting. However, it doesn't rule it out by any means. Fighting can occur one day into living together or 2 years later. Or never at all. If you're 100% committed to keeping them together you must be sure that there are plenty hides so there is limited competition. And be prepared (financially) to have to seperate them.
For cheaper end of reptile goods there are sites like swell reptiles or Surrey pets supplies that will offer you the lower end prices (unless you want second hand).
Leo's do not need UVB but recently people are becoming more likely to use it as studies and general use has proven it to he beneficial. But it's not necessary. For a begginer I'd steer clear of any sand, especially with Leo's at a young age. 100% no Calci-sand as Leo's will purposely eat this as a supplement and its a big risk of impaction.
Again, all these things are guides and the basic needs of a leopard gecko. Many will have different techniques and ways of doing things that work for them. But you'll pick this up as you go along.
The best of luck to you and welcome to RFUK. I look forward to seeing some photos of your set up and your new Leo's
P.s. I'd also highly recommend Repashy Calcium Plus. You've probably read that Leo's need supplements in the form of live food dusting. Usually 4-5 days Calcium dust and 1-2 days multivitamin. What Repashy does it take away the guess work of when you should use what. It's used with every feeding and supplies everything a Leo needs in equal balance. It's also attrtibuted to an increase of activity in Leo's.
If you have any concerns, doubts or worries about your animals health always consult a qualified veterinarian (with the necessary experience).
Nobody can properly diagnose an animal based on descriptions and photos. Especially when those animals, such as reptiles, have a small list of visible symptoms than can be found across a large range of problems.
Always see a vet. Don't let strangers on the internet make you do something you'll regret. They won't take responsibility.