You do not have to add extra liquid to your 50/50 lye solution, unless your recipe has a water discount that's less than 50%, for example 33%. If you run into something like that, instead of adding liquid to your lye solution for that recipe, I would suggest putting that recipe back through a soap calculator and changing the water discount to 50%. Soaping at a lower temperature will help your soap batter stay fluid longer. Yes, oil temperatures matter. You want your lye solution and oil temperatures to stay within 10 degrees of each other. I made a whole video discussing temperatures in my beginner soap series playlist, so you might want to check that out! 💕