You went for the CEC, right? Yes, you would be placed with the Seabees as a vast majority of Reserve CEC Officers are with the Seabees. The Seabees are augmented heavily through the Reserve and you will find this line of work to be incredibly rewarding along with an incredible amount of work. I'm glad to see that you are getting ready for the PT exam. Good. If there is one thing I cannot stress enough.....Do not be a bag of ass in front of your troops. Work hard to be in better shape than all of your troops and always have your uniform in good repair. We are expected to do two things...build and fight. Reserve Seabees augment the AD folks and also deploy on their own. You will find out that you will spend a majority of your Drill weekend taking care of admin and medical issues, along with trying to get field training, weapon shooting and other items in as well. My 2-weeks next year will be spent in CA for my CEC basic officer course and a Battalion Field Exercise, which is spent completely out in the field doing build projects under fire, defensive/weapons training and other nice warfare/wilderness things. Its busy and you will be doing plenty of work outside of the drill weekend. You will be a bit overwhelmed at first, trust your Chiefs.
Do you have your PE yet?