Quite a few questions, looking for advice

6 months of easy -- and most important, consistent -- running, with gradual increases in weekly mileage is a great way to get started.  The endurance/speed dichotomy is a false one.  I bet you can sprint 100m in 20 seconds.  If you could hold that speed for a mile you'd be running a 5:20 mile (roughly).  So you have the top-end speed to go fast -- it's a matter of being able to hold a fast pace for a longer and longer time, and that mostly happens -- especially early on -- via consistent running.

You don't need nutrition for a 40 minute run.  Many people go 90 minutes or more before nutrition enters the picture.  In general, I think that most people err on the side of too much nutrition during exercise, rather than too little.  Don't be afraid of a 'negative' experience (let's call it a 'learning experience') in the form of a workout in which you suffer at the end for lack of calories.  Just don't attempt something like a 4 hour bike ride with no nutrition -- that can lead to a more significant learning experience that you'd rather not experience.

As a general guideline, I'd start with 90 minutes as the point at which you start taking in nutrition.  Then experiment from there.

It is OK for your legs to feel slightly tired during training.  Fatigue comes and goes. Just what for incipient injuries and if you begin to get so tired that you cannot hit your key workouts, then you need to back off.

It is possible to increase bike more than run, and swim more than bike (in terms of percentage increase per week).  The risk of injury gets less as you move from run to bike the swim, the one caveat being that if you are swimming with poor form, you can end up with shoulder problems.

Some do.  Some don't.  I assume by 'rest week' you mean a week of lower volume, not completely off.  If I feel that I need to back off of the volume, I do so, but I do not plan ahead of time to do so.

I'm a beginner also, but this raises a question for me.  It's been repeatedly stressed to me that the rest week every 4-5 weeks is critical.  It lets your body recover and refresh for the next build phase.  Michael, are you saying you disagree with that?

To me this is key.  We all look for the right way to do things but since all of our bodies are different and we all  have different goals there is just simply no one answer to any question. 

Oh, no, I've been running for about a month and a half, now.  I've been increasing roughly 5 minutes per week.  However, once I get to 45 minutes I'm thinking I will switch to distances instead of times.  And the next item I get will be a heart rate monitor, I've been wanting one ever since I started running again.

Thank you all for the responses, very helpful!  So, in a nutshell, listen to your body, steady increases over a longer period of time, and let the "learning experiences" come. 

Yes, I disagree with that.  I agree with what Scout and others said.  It varies.

I've sometimes taken lower volume weeks only a couple of weeks apart, but also months apart.  It varies.

Echoing Michael and others - it varies. The key is to listen to your body, and to what it is telling you about its ability to recover from the stress that you're putting it under. If you're not recovering properly from workouts, such that you're getting progressively run down, slower, lethargic, etc., then it's time to dial things back a bit. If the body is not able to recover, then there is little benefit from the training. Guidelines like "take an easier week every 4-5 weeks" are designed to be safe for the generic athlete, but might not fit your needs, due to physiology, mental fatigue, or other work or lifestyle constraints.

I find that with easing up before races, plus work/life bottlenecks, the less intense weeks tend to take care of themselves, so they kind of build themselves into my training without any additional effort. 

1. in general yes gain your endurance first. to also gain speed do tempo runs in which you run slightly below race pace, approximately 75-80% effort. tempo runs will really help improve on your racing speed over distances.

2. in general for runs under an hour hydrate before, if you have a path with water fountains great!. generally runs over 45min-60min+ i make sure to take in heed to keep myself hydrated and replenished.

3. do what your body feels, if you feel that the amount your doing is good keep at it, if you can do more try, if its too much do less. always remember to rest, i personally take 1 day every week off. be sure to get plenty sleep too!

4.im actually coming off a rest week, i just lessen the distances and go easy during it