If he's planning on selling in 2 years then I don't think that buying either the 3-bed or the 4-bed are a great option to be honest. He'd probably be better of renting for the short term. The transaction charges, loss of FTB status and risk would not make it worth the gamble IMHO.
Ok, my mistake on the FTB status in this case then. I presumed that due to the price range of those properties within the commuting belt of Dublin that they would fall into starter home territory.
There are a still a lot of transaction charges that need to be considered when buying and selling a house in such a short space of time though. He'll easily have dropped a fair few thousand trying to get it decorated, getting the kitchen kitted out, putting furniture in, paying the stamp duty (if applicable; depends on whether new-build and/or size), paying solicitors fees, paying insurance, paying interest on the mortgage etc. He should at the very least do a cost analysis of it all compared to renting and see whether it's worth the risk.
to put it this way, the more you put into an investment, the higher the return can be, or vice versa, your mate can work it out. like any investment theres a chance of gain/loss.
Depends on the local supply in the area. If there's loads of 3-beds but not much 4-beds then the 4-bed would be able to command a good premium. If there's lots of 4-beds in the area then it may not make such a difference either way.
Has he really done the sums? By my conservative calculations, it will cost €40K over 2 years, or about €1,700 a month. Should be able to rent some where nice for this. If the house goes up in value then this figure comes down, but the house market appears to be slowing at the moment? (assume €340K house, 80% mortgate; stamp duty @6%=€20K, Interest @3% = €8K per annum. €4K fees buying and selling).