Stretching and Strengthening - Why/When/How

I got up at 4:30 this morning to do a 1hr 20 min bike ride and a 4 mile run after.  My legs were already tired from the 2 - 45 min spin classes with an extra 30 minutes of med-easy spinning between.  I made it through 5 sets of 1 mile sprints this morning on the bike.  Now comes the run.  I finished, it wasn't as fast as the last couple of weeks' 4 mile brick runs, but I finished.  I knew it wasn't going to be pretty when the first 10 steps made my knees ache so bad.  I thought for sure my IT band was going to start acting up.  Thankfully it spared me. 
Tonight at the gym, I was supposed to do legs and 3 - 1 mile repeats at 6:47 with a half mile rest in between.  I spent 45 minutes working on legs doing the following:

• box jumps - 20
• walking lunges with an 8lb dumbbell in each hand
• hip adductor - 25 @ 70 lbs
• hip abductor - 25 @ 70 lbs
• jack knives with my hands on a plyo box and my feet on a medium sized ball (I love this one for core work) - 12
• single leg dead lifts on the Bosu (this is good for core and stability work too) - 10 each side with a 15 lb dumbbell
• calf extensions - 25 @ 70 lbs
• finished with leg kicks over hurdles

I was hoping that the hurdles would loosen up my legs a little.  It didn't.  My legs from my hips down to my ankles were aching.  The "tired and need rest" aching.  I didn't want to push it since I am too close to my race ro risk an injury now and I still have a lot of long training and hard training sessions left.  I decided to do 15 minutes on the elliptical then stretch and call it a night.
Now to the point of the title of this posting.  Stretching and strengthing your hips and legs are important to reducing injury and pain from running, like IT Band syndrome and Achilles tendonitis.  This is the 'why'.  When should we stretch?  Well, before and after a run.  I like to try and get in a stretch every day, even if I don't run.  It's usually static stretching and sometimes it's just a simple bend over and touch my toes, reaching to each side and forward.  Just a little something to keep from getting stiff. 
Stretching is as important before a run as it is after, though.  I've read in a couple of places that stretching before a run should be dynamic stretching.  I used to do walking lunges but recently read an article that included swinging your legs to the side and forward.  After a run, static stretching is better.  5 Key Stretches for Runners is a short article on pre- and post-run stretches.
'What about strengthening?' you ask.  In my workout, I made sure to do hip work.  This is because strengthening your hips helps prevent IT Band syndrome.  This article, Strengthening, Not Stretching, to Deal With Iliotibial Band Syndrome, talks about it citing a research study that showed success with 23 out of 23 test subjects.  Here's another article with gives the same exercises to strengthen the hips and also steps to test your hip strength - All In The Hips.  I also read about the benefits of strengthening the hips about 6 to 9 months ago in another article.  If I can find it I will update this post with a link.               
This is one reason I like to do yoga. It's a whole class devoted to stretching AND strengthening. 
When it comes to deciding whether to 1) crank out another hour of tempo running or sprints on tired legs OR 2) doing an hour of strengthening and stretching I like going with option 2.  My runs are still getting faster and I haven't had any IT band issues in over a year.  I hope to keep it away for ever.