If you suspect your toilet is leaking, but aren't sure where, add some food coloring to the water in the tank. If you see colored water inside the toilet bowl, suspect a defective flapper that needs to be adjusted or replaced. If it shows outside the toilet near the back, suspect a faulty tank-bowl gasket. If you see any water on the floor near the base, check for a faulty wax ring.
Have a time frame in mind when you buy a home, and let it guide your purchase. If you plan to start (or expand) a family in the near future, a studio is not a good idea. If you want a home in which you can age in place, or want to preserve that option, consider a ranch-style dwelling on one level, rather than a multilevel dwelling with stairs.