I did a year-long stint in Spain a good few years ago. As for the job hunt, you'll want to be dressed casually 'smart'. Make you sure you have printed off several clean copies of your CV that include your phone number in Spain. It's best to get a phone/mobile set up ASAP during the job-hunting process. The big time to hire is typically in September, but I'm sure there will be jobs going in January. Basically, you'll just want to pound the pavement. Be aware of the academias closing for lunch in the middle of the day. You might even consider calling ahead to ask if the Director of Studies will be around that morning/evening. These places do most of their business from 4:00 PM onward, so keep that in mind when you're dropping by.
As for the first lesson plans, there's a good chance the academy wants you to use a certain book. Those books are typically crappy, too! I would invest in a couple great teacher resource books before going over. "Lessons from NOthing" (Bruce Marsland) and "Discussions that Work" (Penny Ur) are great to have on-hand. Tessa Woodward's "Planning Lessons and Courses" is another practical one to have when you need some ideas. There's one about 5 Minute activities, but I can't recall the author. Also, take one fabulous books to help w/ grammatical rules. Michael Swan's "Practical English Usage" and "How English Works" can serve as a resource for you. "How English Works" is great for helping students work their way through a grammatical rule.
Good luck, and don't forget everything you learned in your course!
NB: Be prepared in the interviews to do an impromptu lesson. Pick something now, work it out, and just run with it if you are asked to demonstrate your skills!