I don't follow the CAT issue.
Yes, to the CGT issue. If someone buys/acquires a residential property for €500k + stamp duty, the cost for CGT purposes on a subsequent sale would be €505k plus any legal fees.
If it's a material amount, you probably should talk to a tax specialist.
For example, if dad gives the son a property worth €1m which results in CGT for the father on the disposal and CAT for the son, the CGT paid can be set as a credit against the CAT.
Brendan