I don't think there is a set age, seems more like personal preference, some like them cut around 6 mths and others wait a bit longer for first cut.
If she is in season the excessive hair loss can be due to that factor aswell, Phoebe dropped all her coat and still doesn't look right and her first season was a while ago, and Penny drops after her seasons.
You can hear my dogs feet too when then walk on things like wooden floor or tiles but they are actually short and I think with all the running around that Molly does hers will be ok too, but the groomer, when you find one could check that out.