Can I be arrested for questioning if I am not a suspect?

No. You can only be arrested if you are suspected of an offence. If the police believe that you might have information relating to a crime, they may ask you to attend a police interview; but you do not have to attend. However, if someone else is (or has been) charged, a Court document (called a ‘subpoena’) may be issued requiring you to: (a) attend Court to give evidence as a witness, or (b) produce requested documents if they are in your possession, custody or control

How much force can be used to arrest me?

No more than ‘reasonable’ force can be used to arrest you. The type and degree of force that is ‘reasonable’ will depend on the circumstances. For example, if you are suspected of a minor, non-violent offence (such as shoplifting) and are not resisting arrest, only minimal force can be used eg holding your arm or placing a hand on your shoulder. Any greater force could be considered an assault, and you can lodge a formal complaint (against the police) or press for charges to be laid. On the other hand, if you are committing a serious and/or violent offence (such as a serious assault) and/or are violently resisting arrest, a substantial amount of force might be considered ‘reasonable’; possibly including throwing you to the ground, or causing pain by twisting your arm and/or striking. However, the force must not go beyond that required to subdue you. The police cannot, for example, punch or kick you after you stop resisting them.

Arrest Rights

Who can arrest me and when?
The rights of people held in police custody in NSW are set out in a number of acts Acts and Regulations, including the Crimes Amendment (Detention after Arrest) Act 1997 and its Regulations 1998, and the Crimes Act 1900. Police officers can arrest you when:
they catch you committing an offence;
they have a reasonable suspicion that you have committed an offence, or that you are about to commit an offence;
they have a warrant for your arrest (eg for failing to appear at Court, for a past offence etc);
they know or reasonably suspect that you have breached bail conditions.Anyone else (security guards, store detectives, ‘bouncers’, and all other members of the community) can perform a ‘citizen’s arrest’ upon you if:
they catch you committing a crime;
they see you committing a ‘breach of the peace’; such as obstructing a police officer in his or her duties, ‘creating public alarm or excitement’, or committing an assault. Minor offences such as offensive language, disturbance and annoyance are not sufficient for a citizen’s arrest.

For more information se:
https://www.sydneycriminallawyers.com.au/
or
Contact a criminal lawyer