Stamp duty clawback

Hi, wondering if anyone can help me. I know this has been dealt with in other threads but I am seeking clarification. I know there has been a reduction of clawback from five years to two years for anyone changing their PPR to an investment property. Does this reduction apply to houses purchased before this change in last years budget, say for a house bought in early 2007.
If house is rented and stamp duty is due does the landlord sort this out him/herself or do Revenue notify them of it? All landlords register with the PRTB so do they tell Revenue and do Revenue then work out how much the landlord owe them.
Also if rooms are rented out under Rent a Room scheme can the landlord, who will still be living there register with the PRTB. I know they do not have to but could they for thier own protection? Thanks for any replies

This should answer your questions:

http://www.citizensinformation.ie/categories/housing/buying-a-home/purchasing-a-home/stamp_duty

It's up to you to let them know you owe them stamp duty but they can of course simply look you up on the PRTB database. What would cause them to look into you in the first place I do not know.

Hi - this has probably been covered before but I can't find a definite answer:

I have bought a second hand house with my Fiancee and its our PPR. We paid the relevent stamp duty on the house.

I have an apartment that I purchased as an FTB where I previously resided for the last 18 months. If I leave the apt empty for the next 6 months until the 2 year clawback has expired am I exempt from paying back stamp duty if I decide to then turn it into an investment property? I would intend to rent it out then after that and notify revenue and follow all the appropriate steps.

Also what level of TRS would I qualify for on the house?

Thanks,
JB1