Do I need to 'update' my passport after marriage to indicate the married status?

You can apply for change in name where you can get your marital status changed too! Change of name       If you change your name, please get your passport booklet changed.  Please approach the passport issuing authority concerned in good time. Apply with the following documents: Fresh application form   If you have changed name due to marriage, a self-attested photocopy of husband's passport, if any, or an affidavit from the husband and wife along with a joint photograph, as per prescribed format If you are a divorcee or asking for deletion of spouse's name in the existing passport, deed/sworn affidavit, as per prescribed format, or divorce deed, duly authenticated by a court. If you are remarried and asking for a change of name/change of spouse's name in the existing passport, a self-attested photocopy of divorce deed or death certificate as the case may be in respect of first spouse or documents as above. If you have changed name due to other circumstances, deed/sworn affidavit, as per prescribed format, and a paper cutting (original and one self-attested photocopy) each of two leading daily newspapers, where change of name has been published.

Not otherwise and unless you are required to do so by any foreign consulates when and if you want to go abroad on a 'Spouse Visa' to stay with your spouse already working there on a 'Work Visa'.  Better to carry your marriage proof, viz., marriage certificate, photographs, etc., even though you have added your spouse name in your PP.

Yes you should get your passport updated in view of your marriage from single to married. Your case should fall In clause 4 reissue of passport for change in status.With this a new passport will be issued to you and your spouse name will figure on the last page of your passport.For this you will have to get your marriage registered in the office of the Registrar of Marriages of your concerned area.Schedule and appointment to this effect , attend the same and take the marriage certificate with you.A fresh passport with another validity of ten years wil be issued to you. If you don't get it updated on this account it will amount of concealing of facts which could hamper your interests in future and may create obstacles when you and your wife travel abroad together,,when you sponsor her if you are abroad etc etcThe above is my personal view in respect of your question . You can take your own independent decision irrespective of my above answer as you are better to judge and opt for the future course in the circumstances of your case.

No, you don't "need" to change anything on your passport. However, if you mention your marital status in any other forms like VISA application, etc., then it is always better to carry your Marriage Certificate copy with you.

I guess its not recommended to change the spouse name to fly in US but its always recommended to change the spouse name in passport after marriage if you want to fly in Europe. I have my spouse VISA stamped with h4 dependent Visa. But when we went to get Germany visa they have rejected and said to change the passport name of my wife. Actually problem was due to not her old name on the passport but my kid birth certificate has husband and wife name and wife name is the latest name on birth certificate. Germany embassy is expecting to change the name of wife in kid birthdate certificate of  in passport. I would suggest to avoid this circumstances you should change the spouse name after marriage.

Always a good idea if you are going to travel as a family, for instance, if you are going to US to work, OR, if you are going to apply for visas under a family group thing (with kids). Process - option no 4 is the easiest. However, do you need to? No, unless you define why...

I think you are referring to 'Spouse' section in your passport. If you want to add this detail(I wont go into the grammar of need to vs want to) , then Yes, you have to apply for re-issue of passport . Earlier, small changes in the passport were captured in the observations page. Under the new system (atleast in Karnataka), if you need changes in Name, Address, Addition of Spouse, cancellation of ECR (Emigration Check Required), you have to submit an online application, select re-issue, there chose the reason, then along with other details common to a passport application, you submit. You will be issued a new passport with a new passport number. Recently I had ECR removed from my passport. Earlier they used to just scratch it out or stamp a seal saying ECNR. Now just to remove ECR, they re-issued the passport with new number and new validity.