On posting--two weeks is a long time to wait ;-). My answer would depend on how many mistakes the betas found in the parts they got to. If it was flowing well and there only were a few problems, I would go with posting all of it and taking your chances. But if they found several important things to correct (and it does seem that you've had some struggles knowing where to go with your plot based on previous comments), then post the logically ending shorter stuff. This way you feel a sense of accomplishment but don't get trapped with errors.