1. Assuming he's contributing to the mortgage, I think that's probably possible. Call Revenue to check [but not today - they won't be answering the phones!].
2. If you buy your next house together, it's irrelevant if he's a first time buyer for stamp duty purposes - you won't be and therefore you collectively will not qualify for stamp duty exemption. A few people will try to persuade you that if he buys the next house in his sole name it'll be different - but that's possible [and not certain] only if he buys with no contribution from you to the purchase price or mortgage, and Revenue will probably still examine the transaction very carefully.