I haven't read through all the material on this yet, but do have the following additional tidbits:
The issuer of the letter of credit has an absolute deadline of five banking days to examine the documents and decide whether or not to pay the draw request. (UCP Art 14) Under UCP 500 - the issuer had a reasonable period of time (not to exceed 7 banking days).
The issuer is contractually obligated to the beneficiary under the terms of the letter of credit.
The issuer is required to check that addresses on the letter of credit or any other document are within the same country. (They do not need to be the same address - just the same country).
If the issuer refuses to honor a draw, it must send a notice containing specific information. UCP Art 16. (I haven't read all of this yet).
If I learn any more I will come back here and update. I am just inundated and these were my notes so far.