Is a Leash a Must Have Even for Shih-tzu Dogs?

My family recently bought a shih-tzu dog. All cuddly and very tamed, our shih-tzu dog is allowed to roam around the house unguarded. This is despite the presence of two kids who both loved to play with our dog. Reading your article though on dog leash, i got the impression that having a dog leash is a must have. Here are just a few of my questions related to the topic:

1. Is a dog leash a requirement even for the most tamed dog like a shih-tzu?
2. Is a dog leash training effective to ensure dog obedience? Should this be part of dog training?
3. Are there available flexi dog leashes in the market?
4. Is running dog leash not dangerous to a dog, i.e. would this not cause injury to the dog?
5.As a dog leash is used to lead or hold a dog in check, is this not a form of dog control which could be similar to placing a dog in a dog cage? Will this not increase dog aggression? Or will this be an effective thing to controlling dog aggression?

Questions on Dog Care from a Newbie Pet Owner

The family recently bought a shih-tzu dog from a neighbor. At first I was not interested as I am not an inborn pet lover...not even for the tamest dogs. As taking care of dogs especially shih-tzu is really something new for me, I have here a few questions which I hope you could enlighten me with being a newbie in dog care.

1. AS part of dog grooming, what are the things that I should do to eliminate the odor? our shih-tzu takes a bath once a week only, should we increase the frequency?

2. Is the use of ordinary shampoo and conditioner (for humans) appropriate for dogs especially for the thick dog coats of shih-tzu? or should I really use dog products such as dog shampoo, conditioner, powder, etc? what dog products would you recommend?

3. Our dog is almost 1 year already. Is he prepared for mating already? when is the most appropriate time?

4. We will soon acquire a girl shih-tzu. I this ok for our boy shih-tzu? or are there preparations for our boy shih-tzu?

I would highly appreciate it if you could answer my questions above.