Hi, 

I am applying for a J1 visa for as an phd student to be based in
washington DC for 3 months to carry out some archival research. I am
being sponsored by a university in DC for my J1. Anyway before i do
this research i am flying to a conferance in denver from the UK then
flying from denver to DC. So on my application for the J1 i put my
port of entry was 'denver' . I then booked my flights and noticed that
my flight connected in chicago. So i imagine my port of entry is now
chicago. I have contacted the university and they have tried to change
the form, however i dont know if it will take effect in time.

Does anyone know how critical this is. 

Also related does anyone know about the process for getting J1 status.
I hear that i will recived a ds-2019. what is this? and will i need it
in the UK before, i go, will i have to take it to the US embassy in
london. and what would happen if my port of entry was different
because i took a connecting flight.

any suggestions would be appreciated.

Its best to contact one of the  many  US immigration attorneys you can
access online. Some of them will provide a free first time 10 min
telephone consult with regards to a j1 waiver inquiry.

J1 Waiver employment opportunities
http://www.mdopts.org