a. No CGT, no Stamp Duty. Possible exposure to CAT (inheritance tax) depending on the value of the farm, and whether you qualify for agricultural relief ( which is the farmer test as above currently).
b. Possible CGT, Stamp duty unless you qualify for YTF relief, similar CAT except a small gift exemption of 3000.
c. Exemption from Stamp duty IF you qualify on the other conditions- which is to say that you must actually be farming ( a certain percentage of your time) and be under 35 etc- look up conditions on revenue.ie
YTF relief at present ONLY availabe to people under 35 at the date of the transfer.
All above just general. You and your father should really take professional advice.