(1) NIB product is for PPR only.
(2) It's both illegal and risky - and what's more, it'll cause you problems with Revenue (if you try claiming TRS - and the mortgage provider will wonder what you're up to if you're not claiming TRS, not to mention rental issues), plus there'll be conditions on term life assurance, etc. Don't do it.
(3) Depending on the amount in question, you may be able to negotiate a better introductory rate, though the best I've managed is a two year discount tracker of ECB + 0.85% from BoI - but that's rolling to ECB + 1.25%, which isn't great. If you can get ECB + 0.9% for the full term, that sounds pretty good to me.