Yes. If you are asking if dental insurance will pay for what you currently need, the answer is not usually. There are typically 1 or sometimes even 2 year waiting periods. Initially insurance covers prevention in most cases.
Yes. There are many insurance companies that offer a host of plans for dental benefits. If you belong to a group, such as an employee of a large company, it is much easier to get dental insurance than on an individual basis. In either case, there may be a "waiting period" prior to receiving partial dentures. If you can't get insurance, many dental offices offer payment plans. Talk to your dentist.
Yes. You can still get dental insurance but you may want to check for exclusions on the policy such as missing tooth clause or a waiting period for major work which partial dentures fall under.