I'm going to start a bit at the beginning for answering, you seem to have a few different questions going on in this post. Forgive me if I cover a basic amount of information that you already know.
Each oil has its own SAP value. SAP value is the number of milligrams of KOH (potassium hydroxide) or NaOH (sodium hydroxide) it takes to convert or "saponify" a fat into soap. KOH and NaOH may both be referred to as "lye", the difference between the two is if you want liquid soap (KOH) or solid soap (NaOH). When using an online
soap calculator, you will tell it what type of lye you are using, what oils you are using, and what superfat (SF) you want to include in your soap. SF is a percentage of oils that you do not want converted into soap. (The reasoning for that is a whole 'nother story that I won't go into here, but I will tell you that most soapers use 3-8%, depending on oils and personal preference.)
The calculator will give you a lye quantity. That is completely based on your oils. For how much liquid to use - or lye concentration - that is dependent on you. You need an equal amount of liquid to completely dissolve lye. (e.g. if your lye is 2 ounces, you must have at least 2 ounces of liquid to completely dissolve it). I use water to lye ratio (water:lye) for my recipes because it is easy math for me if I need to adjust my recipe on the fly, but others will use lye concentration, or the less accurate 'water as % of oils'.
My personal preferences:
2:1 for a single color soap that only needs to be mixed and poured.
3:1 for swirling colors or designs
4:1 for really tricky FO's if I want any chance of a design
These are what work for me using my soap recipe and soap methods. Others will have different preferences based on their recipe and methods, so you may get a lot of differing advice. None of it is 'wrong', so take the time to play with your soapmaking to find what works for you. Start with small batches