Payment processor option

Hello. I own a street food caravan since 2014.

The payment of payments has evolved a lot. Our customers ask us to make the card payment available.
We are not sure if we should opt for square-up, paypal or other types.

They want to implement EMC particularly contactless. My questions are

1) How many contactless payments can be claimed before customers are asked to insert the PIN number. This is a problem because we want to keep a fast flow.

2) Dealing with friendly fraud

3) In terms of both of the above, the payment processor is the "friendliest" when it comes to chargebacks. We read horror stories in which companies ALL blocked their funds for a chargeback and went bankrupt because they could not keep up.