Mid April C&O bike itinerary help

I am taking my 10 year old daughter on this April trip in less than 2 weeks on her spring break. We never biked on the towpath before. We want this to be an adventure. Need your suggestions on itinerary, etc. We have about about 7 or 8 days. We'd like to take time to do something more than biking: hiking, attend ranger programs, visit historical sites and parks, etc.
Day 1: Someone drop us off at Cumberland: visitor center, museums. Stay in a hotel for the night.
Day 2: Bike about 40 miles to Little Orleans. Stay in a hotel there. Spending time in Paw Paw for a couple of hours. Would we have time for the Paw paw tunnel Hill Trail?
Day 3: To Williamsport and stay the night. Stop by Hancock visitor center. What else?
Day 4: To Harpers Ferry and stay in a hotel. Stop by Shepherdstown (what to do there?)
Day 5: Spend some time in Harpers Ferry. We love it in HF. Should we spend another night here or stay in Brunswick or Point of Rocks?
Day 6: To somewhere around DC. But where? Seneca?Potomac? Bethesda? We'd like to do the whole Billy Goat Trail.
Day 7: Stay around DC for another night. Where?
Day 8: Wondering around and see what else we want to do. Someone will pick us up from DC.
From Cumberland to Geogetown, is it slightly down hill? Is it ok for my daughter to use a regular bike with no gears? Is it going to be real muddy if it rains? We are going to pack our clothes in the backpack and carry it on our back. Is it going to be too heavy if we had to ride 40 miles a day? Do I have to wear a helmet?

Feel free to give me a call and I can share some info that might help in regards to you upcoming ride. I've ridden the Passage 4-5 times and the c&O several times. I can pretty much answer your questions but it's easier to talk than email as your ideas generate other questions. You could call me any time after 5pm 757 619-5522. I'd be happy to help.

Thank you Rick. I probably will give you a call tonight. Thanks for your time!