Exercises like this should keep you busy for a while but they become tiresome too. Keep this exercise in the back of your mind for those times when you need to brush up on your picking. All three of the above exercises use the same exact picking pattern. Even when changing strings you should play the 1 note with a down-stroke. In this exercise, you should be using all 4 fingers in your fretting hand.
Most people have trouble getting their pinky strong enough to fret with.
With some patience and time you should build up enough strength. The above exercise need not be done at excessive speeds but it should be done consistently. You might want to get yourself a metronome to keep you on the right beat. There is a picking technique that when executed correctly will produce a harmonic. This harmonic will make the note sound much higher and sometimes blends with the original fretted note.