how much detail to include in CV

[/sigh/twombly]

I'm a little perplexed by the process of converting my resume into a CV for my applications... I have a pretty good grasp on what I should include, but what are your thoughts about how much detail is necessary (and how much is too much) for a CV from someone who has only completed undergrad?

Should I include a list of relevant coursework and the research projects completed in those classes? Abstracts for my senior thesis/another research project? Descriptions of duties at different internships like in a resume (or just list the internship title and location)? Should I go into detail about skill levels for languages I speak/read? 

Trying to strike a balance between clean, short, and professional and including all the relevant information ( don't want to just dump a bunch of details that could look like filler).

[fuzzylogician]

Most undergrads will have a fairly short CV. Look at some CVs of beginning graduate students at your target programs to get a sense of what to include. As for your questions: 

• No need to include a coursework section unless you were asked for one.
• Don't include abstracts of your thesis or other projects. That might go in your SOP but not your CV. 
• You might include very brief descriptions of your responsibilities at internships, provided that they are related to your field in some way. 
• Are languages important for your application? How much detail to give will depend on the answer to this question (usually, the answer is "no details" but it might depend). 

Generally speaking, give information about Education, Presentations and Publications (as one heading unless you have enough to separate them), Grants/awards/honors, Teaching experience (if any), Research experience (if any), Service and memberships (if relevant to your field), Languages. Again, look at what others are doing in your field for the most targeted advice.