This is probably a dumb question, but does one earn EQM miles when flying on codeshare on another airline's metal? Also, what if it's on *A airline where UA does not fly, like DEL? Thank you.

if you fly on a *A-operated flight, you most like ly earn EQM. See the master thread here: http://www.flyertalk.com/forum/showthread.php?t=445613

http://www.united.com/page/article/0,6722,1177,00.html
This page should answer all your questions.

Yes, you will earn EQMs on another *A carrier and it doesn't matter whether UA flies there. When I fly to a European destination, I almost always fly LH onward from FRA or MUC and always get EQMs--well, almost always. If the LH flight is a codeshare operated by a non-*A carrier (as happened to me this summer on the way to Belgrade), no EQMs will accrue (check to see who operates the flight). Also, different carriers offer different levels of miles (including EQMs) based upon fares. This past spring I flew SAS from Copenhagen to IAD and got only 25% of the actual miles, either as redeemables or EQMs, because my fare was deemed to low. So check with the airline before you buy. A higher fare class is likely to get you the full mileage quotient.

I'm not sure that's a hard and fast rule. I've always received EQMs on Air Dolomiti flights bought as a LH flight. As far as Mileage Plus knows, it's a LH flight, plain and simple.

This may be a special case, because I believe LH owns at least a part of EN.