Is it possible for child to have strep w/o dore throat or fever? has very faint non itchy rash on torso and face, congestion

Not likely: this is more likely a viral rash. Young children can get scarlet fever, which is a strep infection that can cause a sandpaper-like rash, but as the name implies, children will also have fever with this. Remember that many children (15%-ish) will test positive for strep in their throat even if it is not causing any symptoms.

Yes, it is possible: Individuals have different pain thresholds/tolerance levels. It is entirely possible for a Strep to be present without a significantly sore throat, although this is obviously less common than the classical symptoms. Strep 'carriers' are often infected with sub-clinical or no symptoms but have intermittent flare ups of pain. Strep throat in all forms requires treatment to avoid complications.

Yes and no: The problem comes in separating the person with congestion from a variety of causes. There are people that carry strep year round without ever getting sick or any consequences from strep. The numbers range from 5-30% of people depending on the time of year. Faint rashes on face & torso are often due to viruses.