Have there been any conferrals of the equivalent rank in the other two services? Something that should be in the lead and body.
In the infobox, with the the equivalent ranks, air force is listed above the navy? Is that the order of seniority of the three services in the Indian Armed Forces?
Where you use an initialisation, such as CDS, the initials of the initialisation should all be in initials capitals ie Chief of the Defence Staff, same later with the COAS, and once you've used the acronym, use it from then on
Where are the five stars in the infobox actually used? car pennants? This should be explained in the body of the article.
suggest using the same nomenclature for COAS, unless it changed between Cariappa and Manekshaw's terms, Cariappa is mentioned as commander-in-chief
In 1947, when Carippa took over, the position was called commander in chief, later it was re designated as COAS
If I remember correctly, Manekshaw didn't actually command 3/5th Gorkha Rifles, so it doesn't make any sense to include that
field Marshal should be field marshal, and later field-marshal should be field marshal, be consistent in the article
per WP:LEADCITE, I can't see anything that needs a citation, so long as everything in the lead is covered by information in the body of the article (which is required). Suggest ensuring that everything in the lead is covered in the body first, then eliminating the citations from the lead.
2a. it contains a list of all references (sources of information), presented in accordance with the layout style guideline.
assuming all information is cited in the body (instead of only in the lead), this looks ok.
2b. reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose).
there is a typo in the citations, Orbituary should be Obituary.
what is the underlying copyright on the design of the FM rank insignia?
The rank was established on 26 January 1950, and is a PD now in India, I have added the tag. Please see the commons page of the image. Also for the following.
what is the reference for the design of the FM rank insignia and the star insignia in the infobox?
Per the Manekshaw GAN, the Indian Army website doesn't explicitly allow derivative works, so the Cariappa pic needs approval from the Indian Army and an OTRS tag. I don't think it can be used under a non-free use rationale.