Blanche!
I'll echo everyone else... it will take time. Years ago, we got a new neighbor to the one side. She had a friend that was a landscape architect that drew up a showpiece plan for the yard. I kept reminding her that it was not an overnight process. When she would ask how long it took to do our yard, the usual response was more than 10 years and we're not done. We convinced her to take her time and do what she was comfortable with as she learned. Over the years, she has learned quite a bit, but mostly that she will always learn something new.
Getting back to your situation, Bill has the right idea. Start in the front as that is what the world sees. Then work your way around the property. You will find that as you finish a section, it will inspire you to move on to the next and probably re-visit the 'completed' sections. Your plans will change with every season. Some things will make it, others will not. Have patience. It takes longer than you may want, but will come together sooner than you think.
If you do decide to get rid of the chestnut, check with garden centers in the area and see if they know of someone that would be willing to 'buy' the wood. If so, they will most likely give you a better price on removal. They might even bring in a portable saw mill to rough cut the trunk into boards as they go.