Copper Mountain base elevation is 9700 feet so the high altitude is definitely a thing! It typically takes about a day to adjust to the altitude but things that can help are: 1. Stay Hydrated. If you think to yourself, "Have I had enough water today?" then no you haven't so drink more!, 2. Getting a good night's sleep will help with the adjustment because you will definitely feel tired, 3. Extra electrolytes help as well (either Gatorade or liquid IV), 4. Pack sunscreen! Being at a higher altitude you are much closer to the sun, and are more likely to get a sunburn.
Weather at Copper this time of year of typically around 55 degrees and sunny during the day. At night temperatures can drop about 10-15 degrees so please pack accordingly! I recommend checking the weather about a week prior in case you need to add or take away warmer clothes. Colorado weather is really unpredictable so it is really good to keep an eye on it before coming out here!
Summit County offers a free shuttle service that goes between Copper Mountain, Frisco, Breckenridge, and Keystone that is available all year round. Shuttle details and schedules can be found on Summit County's Website: https://www.summitcountyco.gov/360/Bus-Schedule