Can we have a catholic church ceremony/blessing without legally getting married?

You’d have to ask your priest, but usually the answer is no. Some priests will perform a convalidation- a blessing after your wedding so that the church views your marriage as valid. This requires paperwork and some priests will still require marriage prep counseling with them in order to perform this. They won’t perform a ceremony without the legal side if you aren’t married already.

There are usually strict rules about having made all of your sacraments before getting married in a church even if you are already legally married and doing a convalidation ceremony. You'll have to check with your local church.

That is something you have to ask the priest but be prepared for them to say no. At least one of you must be a current practitioner in good standing, and you must attend premarital classes through the church among other things you must agree to. They will not do a wedding “for show” only. The parents’ religions are moot because they are not the ones getting married.

You can't and anyone who says yes will be lying. You shouldn't get married in a church if you don't believe in her teachings, that's very disrespectful. The doctrine of the Catholic Church is clear, if you are not legally married to the person or one of the partners is not Catholic this marriage means nothing and everything is just a theater.

Normally that's not possible. It depends on the country though... The priest or even a pastor should ask your marriage licence before the ceremony.

I know someone that was able to do it without marriage license but I believe the priest was sympathetic because the bride was illegal immigrant. So you definitely need to have at least the marriage registration the proves your intent to legally marry. The church will also ask you to become a partitioner when you officially become member of church and make weekly donations at mass with their member envelopes. But don’t feel pressured by it as long you show you are an active member.