Hi Carlos,
1. Yes
2. Done courses can't be add directly as I know, may be you can implement course completion criteria and add enrollment period of user in you CSV file then run the cron for the course completion
3. You may add below fields in CSV for users.
User & cohort: firstname,lastname,username,email,password,auth,idnumber,institution,department,city,country,timezone,lang,mailformat,maildisplay,maildigest,htmleditor, autosubscribe, skype,msn,aim,yahoo,icq,phone1,phone2,address,url,description,descriptionformat,interests,oldusername,deleted,suspended,alternatename, lastnamephonetic,firstnamephonetic, middlename, group1,cohort1
Courses:
course1,type1,role1,group1,enrolperiod1,enrolstatus1
See details here: https://docs.moodle.org/36/en/Upload_users