Sakshi,
I wouldn't be able to give you much of an input with regard to CS, since I don't have much experience/knowledge of what comes in your way, in terms of job offers, after having done a CA+CS.
My 2 pennies worth would be, a CS will give you more of a compliance/regulatory profile, as it is, with respect to the syllabus you'll study. The role of a CA is much too different. In fact, a CA+CS might have given you an additional advantage, if you were inclined upon setting up your own practice. In the Corporate world, a CS and a CA are given segregated roles, so having a CS while being recruited into a field specified for CA's isn't going to give you much of an edge.
A CFA, on the other hand, as expensive as it is, will quite possibly land you a job in Asset Management/ Portfolio Management at a Fund/ Investment Bank, which is a completely different field. A CFA will only be handy then.
With regard to your question.
1) A CA is not exactly better than a CS. It's like comparing apples to oranges. A CS is often responsible for compliance, as I've mentioned before. So no, a CA is not better than a CS when it comes to compliance and regulation. But, in general, if you're not doing a CA/CS-specific job, recruiters tend to be more inclined on hiring a CA rather than a CS. In such a scenario, a CS will undoubtedly give a boost to your CV, but not by much, and only when you're put up against other freshers.
2) There is no guarantee. Like I've mentioned before, and I know I'm being somewhat general, it depends on the job you'll be recruited for. For instance, if you're being hired by a Financial Services firm for P&L building, a CS would not add any advantage to your CV, ceteris paribus. On the other hand, if you're being recruited for Accounting & Compliance, a CS will definitely give you an edge, from the point of view of a recruiter.
3) A CS's job in a company is specific. For instance, for a company with a paid up capital exceeding 5 crores(if I remember correctly), a Compliance Officer with a CS qualification is necessary, and that gives you an impression that a CS holds a more senior position, because there isn't a specific position built for a CA. There are no requirements for Companies to hire a CA for a position specially made for a CA. A CA, on the other hand, will be recruited for Internal Audit, Accounts and Finance, all degrees which make no mention of a CA specifically, which leads you to believe that CAs don't hold a senior position. In fact, CA's make good C-Execs, Financial Controllers, Internal Auditors, all of the positions in which a CS is not sought after.
4) Given your scenario, I don't think adding a CS would benefit you as much as having a solid experience, since I'm assuming you're already a working professional. Focus more on working in a better field, because that alone can guarantee you a better package in the future. A CS, at this stage of your career, isn't going to add much weight to your CV, unless, I reiterate, you're specifically looking for compliance and regulatory jobs, in all which then, a CA doesn't give you any more of an advantage.
So yes, it's all too general and depends on what's the kind of work you're looking for. As a rule of thumb, a CS will only be handy in profiles of compliance, whereas a CA is more generally preferred for other roles.
I'm looking forward to some input from more experienced professionals.