In other words:
- inputs are locked
- outputs are locked
- amounts are locked
- nobody will be able to spend the specific txid and vout to another output(s)
- nobody can find out the private key of my spending addresses
All of this has to be correct, otherwise anyone could do the same right after you broadcast the transaction (which also makes it public).
what is the safest way to check that all inputs are signed and the transaction can be broadcasted and it won't generate an error? Can I test the transaction will go through without broadcasting it?
I would use
coinb.in after downloading it and copying to an offline air-gapped system running frmo a Linux LIVE DVD.