it means blood that is still trapped in your muscles has dried to the inside of them. always stretch well before and after working out to avoid soreness.
Weight training will not stunt your growth. However, that does not mean that it is advisable before the age of about 16.
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Yes, this means your body was challenged and its used to being worked now. Try doing a different training and if your lifting weights add some more weight.
This is because the first time you do weight training your muscles are just getting used to the contraction and expansion from using weights. The second time you do it, you are typically going to be sore. Although being sore, shows that your muscles have been working right when you were using weights. The soreness is what makes you feel weaker.
The main symptom of weight training is the urge to lift heavy weights. It's not like it is a medical disorder or anything! Unless it is like an OCD or something! If you lift a lot of weights, your muscles might become sore for a while.
The one you do at home with no knowledge or training.
Weight lifting
The simple answer to the question is yes you can but it depends. Typically you should not do speed training before weights primarily because speed training should be done when you fresh (not fatigued) Doing weighs before will tire you. However, there is a training effect called "Potentiation" which basically mean that if you excite your muscles through weight training before you do a sprinting effort your muscle will produce more power than without the stimulation - more force means that you will run faster. Of course care has to taken with how heavy the weight is and the volume of the session.
weight training strengthens your skeletal muscels
You can't prevent them but you can relieve some of the soreness. Soreness is generally due to lactic acid buildup. To stop this buildup stretching and icing after weight training will help. Stretching and being flexible will not only reduce soreness but also reduce the chance for injury.
For free weight training I would look in to http://www.sparkpeople.com/resource/fitness_articles.asp?id=1033. It is a very informative article that discusses the benefits of weight training and gives you tips on weight training.
Yes.