I have one question, Can I take immigration style photos in US as long as the photos meet the requirements or do I need to take those pictures in Chennai?
{Yes you can take in US and carry them along with you, if don't consider the cost difference}
Do we need to take normal passport style photos for medical?
{ Yes }
I had some vaccinations done but do not have records for them, Do I need to take vaccinations again from the doctor in Chennai for all of those that I do not have record even though I am immune for some of them?
{ You can explain to the Doctor and he/She will decide what is needed for you at your age }
Do we need to take an appointment with the doctor from here for the medical checkup?
{Not necessarily but it is always adviseable to take it }
Also for how much amount do we need to take DD for courier? We are two people me & my husband.
{Its always better to check with the consulate people or the website for the latest info }
I have valid H1 and I-94, pay slips but My Visa expired more than one year ago, So to have a back up plan I am also planning to take an appointment in Delhi consulate for Visa stamping of H1 .So that incase cp didn't go well I can still take visa and come back, Any suggestions?
{IF CP doesn't go well for some reason then your H1B also goes along with it, so no use of that.
There should not be any valid reason of you not getting it (GC) but it can be delayed if they find any missing documents }