You should take advantage of that opportunity. Madrid has one of the best nightlifes in Europe, along with Lisbon, Barcelona and London... The spanish chicks in madrid dress little skirts and high heel boots, but also use alot of makeup so sometimes you can be fooled... they go out in large groups, hooking up with some of them shouldn´t be difficult, taking them to bed is another question... plus, you´ll find much younger peeps going out at night than in America or northern europe, so be carefull for older brothers, ahaha... The bodybuilder look isn´t as popular in southern europe as in other countries... but if you´re blond that will help, because the vast majority around here has dark hair.
Lodging and renting cars shouldn´t be difficult, but again i don´t know what you´re looking for... why would you rent a car? Madrid metro works very well and isn´t dangerous, plus it covers alot of ground. I don´t know what type of room you´re looking for...