My dissertation focuses on the detection and characterization of new transiting extrasolar planets from the KELT-North survey, along with a examination of the processes underlying the astrophysical errors in the type of radial velocity measurements necessary to measure exoplanetary masses. Since 2006, the KELT-North transit survey has been collecting wide-angle precision photometry for 20% of the sky using a set of target selection, lightcurve processing, and candidate identification protocols I developed over the winter of 2010-2011. Since our initial set of planet candidates were generated in April 2011, KELT-North has discovered seven new transiting planets, two of which are among the five brightest transiting hot Jupiter systems discovered via a ground-based photometric survey. This highlights one of the main goals of the KELT-North survey: to discover new transiting systems orbiting bright, V<10, host stars. These systems offer us the best targets for the precision ground- and space-based follow-up observations necessary to measure exoplanetary atmospheres. In September 2012 I demonstrated the atmospheric science enabled by the new KELT planets by observing the secondary eclipses of the brown dwarf KELT-1b with the Spitzer Space Telescope. For the first time, these eclipse observations demonstrated that hot, transiting, brown dwarfs have atmospheres similar to other, cold, brown dwarfs, and not to hot Jupiters. This opens up the use of the transiting brown dwarfs as objects of comparative study relative to the directly imaged cold brown dwarfs. Additionally, the strong focus on statistical repeatability I brought to the design of the KELT-North candidate selection process means that the results from the survey may be used in the future for a rigorous statistical analysis of the new, and old, transiting planets discovered by KELT-North. This will be only the fourth such analysis done using a transit survey, and, with approximately 80,000 target dwarf stars, will use the largest sample size to date. As a prelude to this project, my dissertation also provides the first a priori, descriptive, formulation of the astrophysical sources of uncertainty in radial velocity measurements. Exoplanetary masses are typically measured using radial velocity, and a thorough understanding of the sources of error in these observations provides crucial insight into the selection biases in searches for extrasolar planets, and allows for the design of more efficient surveys in the future.