Hi WST,
lots of valuable inputs here ! Always remember that in any case communication plays a major and vital role. If you don't feel comfortable with the situation and you feel like you're not able to manage it then speak up. ATC will help you most of the time giving you extra track miles and your Captain will help you suggesting actions based on his experience. Always use all your available resources. With time and experience you will be more confident and you will be able to anticipate more and therefore be more comfortable in a different variety of scenarios. Communication will save your day till the end of your career and it's free of charge. If you plan to reduce your speed to green dot for energy management in a busy radar airspace with lots of traffic around you (especially behind you) then a call to ATC stating your intentions will be very helpful to them and to all the other traffics for effective separation. This is just a simple example of the variety of scenarios where an open communication with all the agents involved will reduce your workload and provide useful elements.
Cheers !