The e-visa process can be done online. There is more information in the India forum, but from what I read the turnaround less than one day from the time you submit your application and payment, and the confirmation gets sent to your email. Once that is done, you have to print the confirmation and proceed to the visa counters on arrival. You can go through the process starting 30 days before but not later than 4 days before you arrive. You do need to upload a photo with the application.
That being said, if you intend on making frequent trips to India it could be wise to get a multiple entry visa from a consulate, as the e-visa is a single-entry visa and can only be done twice per year.