Hi Gabor!
Compliments for the home page design.
As for the applicants, you can use the user type for them. Once they are registered, you can enable the Apply button, which can trigger the Job Application form, and take the Job Announcement ID as a hidden parameter (a Job ID field with some HTML typography and *value* might do the trick). Simply put, your visitors-job applicants will create a new content type Job Application, which contain Job ID, their ID (user id) and a brief (or longer) text, such as the one in job application letter.
Also, that way you might keep their CV, and also allow the firms offering jobs to see the applicants as articles related to their job offers (since firms would have another access level).