I cannot speak for the program in Houston, however I did a month at Southwestern. The month was very good (they are on a block schedule so I did 15 twelve hour shifts). The only limit on what you are allowed to do is how aggressive you are. I was allowed a couple of intubations, a couple of LP?s, numerous central lines, I&D?s and tons of suturing. When you are on the trauma side you can evaluate the high level traumas with the trauma team. Southwestern sees tons of pathology, on one shift I saw a probable MS and a hydrofluoric acid burn.
As for letters ? Paul Pepe is well known in the EM field. (designs protocols for dealing with the president) I didn?t see him very much, but I bet you can get a letter from him with a little bit of persistence.
Hope this helps