Yes, but... They will all fall out if there is a permanent tooth under it to replace it. If there is no permanent tooth or the permanent tooth is in the wrong position the baby tooth may not come out on its own. If you are concerned you can see a dentist for x-rays to determine where you stand.
Not always. The timing and order of eruption is extremely important. If baby teeth lost early, late, or in wrong order, can cause malocclusion. 1st orthodontic evaluation age 7. At any age, if you have concerns about size, shape, positions of teeth and/or jaws, see an orthodontist for (free or low cost) examination. You have questions, a qualified orthodontic specialist has the answers.
Maybe. You aqre an adult. At your age, the baby teeth are in for good. You probably don't have permanent teeth under them.