CTP or regular GST registration

Hello everyone,

I have three queries, some made-up situations; please resolve-

A trader having business in UP goes for exhibition in another state:

1. If he's unregistered in Delhi. Will he require CTP registration or regular registration for the exhibition?

2. If he has a composition scheme in Delhi. CTP registration or regular registration for exhibition?

3. If he's registered in Delhi, then will he charge IGST in another state?

Thanks

Manish