For the lower back, you can do deadlifts, back hyperextensions, and good mornings. Squats will also give you a solid core workout.
Absolutely an intense back workout will impact a followup
shoulder workout. Aside from what Klinger mentioned (particularly the
rear delts from rows), you have to realize that you are running on a finite amount of energy. Although you may not be targetting your next muscle group during a workout, you are still emptying your available tank of resources.
I suggest planning more effecient splits. Common ways to use the fatigue of a back workout, for example, to your advantage are to follow up with biceps and forearms. Your grip and biceps will get A LOT of indirect work from most back exercises. Rows, pullups/chinups, and lat pulldowns all put a good deal of stress on the biceps. By the time its time to work them, you'll be able to finish them off with just a few sets.