1. See explanation and sample answer in the ‘Questions’ section.

2. In order to establish context, you must look at the construction of the whole sentence: which is the subject? There is no verb in the phrase, so 'die .....Leute' could be either subject or object. Look for the verb! For syntactical manipulation, you could make the participial phrase (Hochdeutsch sprechenden Leute) into a relative clause: Leute, die..... You could also put your reformulation in the passive voice.

3. Es geht zu means 'things are...'. The phrase in context means that people adjust their way of speaking to the situation they are in. In your explanation, you must state these situations.

4. Read around the phrase in order to find the subject for the verb in the phrase. Note that gelten takes a dative object. (See 'Just-in-time Grammar for verbs taking a dative object). So you need to look for the dative object, which is an indefinite pronoun. Synoymous expression for in der Sprache Spuren hinterlassen: sich in der Sprache bemerkbar machen