Hello, most times lumps in locations that you are seeing in a non spayed dog should be removed as they could indicate breast cancer. Especially if they are growing and getting larger. It is hard to say for sure if she will die due to the lumps but if they are cancer they may just keep coming back even if they are removed or the cancer could spread to other areas of th e body if they are not removed. Anesthetics have come a long way and most vets have very nice up to date monitoring systems for them as well while they are under. They can also sedate lightly at first and then get her on some gas to keep her maintained at a safe level. The gas is excreted out of the body as soon as she starts breathing pure oxygen. Blood tests prior to the surgery could also help the vet determine which drugs to use and how much of it to use.
With all of that being said though she is an older dog at this point and there is no guarantee that even removing the lumps will increase her life expectancy or anything so you should also take that into consideration. So, it may be more beneficial to not do anything about the lumps unless they get infected or ulcerated and just let her live the rest of her life with out worry of being sedated or how she will do under sedation.
The snotty nose could be related to the lumps especially if they are cancerous. It is hard to say for sure though so I would not want to speculate on that at this point. It could also be related to an infection in the lungs or sinus area of her body as well so it would be hard to say if they all were related to the lumps. I would discuss the pros and cons with your vet though. You may want to get an x ray of her lungs to see if they are cloudy or clear. The way the lungs look will help the vet tell you more about what is going on with her.
I guess all in all you have to weigh your options. Removing the lumps may not permit her to live longer so it may not be worth the hassle or the worry. I would discuss with your vet your concerns and see if he feels that removing the lumps will help her live longer or not. Please be sure to let me know if you need anything else.