I think the confusion in terminology comes from Daniels-style workout definitions, where “interval” workouts describes repeats done at roughly 15 minute race pace and “repeat” workouts describes repeats done closer to mile race pace. Anyway…
The duration of the interval or recovery period depends on what you need to complete the workout as desired, which is greatly affected by your current fitness level. In the end, your body knows what's right. I'll refer again to this article for the method I prefer. Don't tie yourself down to something, your body knows what's right. Start your next repeat when you're ready.
As for the types of workouts, there is no best. Any plan that doesn't include all of the workout types is one that is short of ideal. When determining which should be done with more frequency, that comes down to balancing your strengths and weaknesses. You need to do enough to maintain and build your strengths while focusing on improving your weak points so they are no longer limiting your performances.