Keeping lean is about eating the right amount of cals and doing enough exercise. It's not about eating as little carbs/fats as possible. You still need a good ratio of pro/carb/fat which is suited to your bodytype/metabolism, you just adjust calorie intake to suit your needs.
Yeah oats is a good carb source, add it to breakfast. Drop the protein down though to either the shake or the egg whites, no need for both. Nothing wrong with whole eggs either by the way.
Sweet potato is a good carb source, use it post training. Pre training for convenience could add some oat cakes to your cottage cheese/yogurt or oats again.
Nuts are a good source of fats yes, but try to vary it so you could try oily fish, fish oils, nut oils/butters, extra virgin olive oil.
Cottage cheese prebed would be better than a protein shake unless your protein is casein based.