Managing your power budget is a normal part of electronics projects. You can only draw about 500 mA total from the USB port, and less than that from the 5V line if your Arduino is powered from USB. If you drive your Arduino with ≈7V into the barrel connector you might be able to pull a full amp from the 5V rail, but it depends on how hot the voltage regulator gets. The higher the input voltage into the regulator, the more heat you generate for a given amount of current. On a genuine Arduino board the voltage regulator should have an overheat protection circuit, which will cause it to shut off when it gets too hot. Cheap knockoffs may just burn out.
When you start using higher current devices like motors or LED strips, it's usually a good idea to switch to a separate power supply for those devices. Tie the ground lines together, and since you use separate power supplies for the Arduino and your other devices, they don't affect each other's supply voltages.