Re: revenue
In cases of (alleged) fraud or negligence, Revenue can go back as far as they like in pursuing errant taxpayers for arrears. There is no "statute of limitations" as such. This is why some people who held Ansbacher accounts or bogus non-res accounts as far back as the 70s have had reason to settle with the Revenue in recent times.
The Revenue have no authority whatsoever to initiate criminal prosecutions in Ireland. This is the responsibility of the DPP. Nor have the Revenue the power to convict anyone of an offence or to punish them, (apart of course from the standard interest, penalties and publication arrangements which apply to tax arrears settlements). This is the responsibility of the Courts Service.
Hence it is incorrect to blame the Revenue if you think that not enough people are going to jail for tax fraud.