How good is saline solution good at killing bacteria, viruses and other microorganisms? If I use 100% concentrated saline solution, can that solution sterilize everything? And what about salt dissolved in vinegar?

0.9% saline and 5% vinegar will get rid of most household microorganisms but there are some that will still persist so it depends on what you're trying to get rid of.

Considering salt alone, as Reetika says bacteria and other microrganisms in general survive a range of salt concentrations. Microorganisms called halophiles optimally grow in the equivalent of 0.85M NaCl (~5% w/v) and tolerate up to the equivalent of 5M NaCl (~26% w/v), concentrations well above that of isotonic NaCl (~0.9% w/v). It will depend on the type of microorganism but I doubt you will normally encounter many microorganisms that will be happy in saturated NaCl! (~26% w/v, ~5M). I think most strains of E.coli don’t like NaCl concentrations much above 0.5% but these may not necessarily kill them - there are many variables such as growth matrix (e.g., liquid/solid), stage of growth, temperature and possible ‘adaptation’ to high salt concentrations.