Hi, 1. You can't but even if the new purchase was in your wife's sole name, this would not change matters s married couples are seen as one person, for Stamp Duty purposes, so she would still have to pay the enhanced rate.
2.You can transfer your share to a third party, but I am afraid all owners of a property have to be aged 18 or over.
3. even if you owned only 1% share, you still own an "interest" in the property, so you would be liable for the enhanced rate of Stamp Duty.
4. it will be on the whole purchase price, I'm afraid.
5. You won't be able to claim the extra enhanced element back if you dispose of your interest in the other property at a later date. The only scenario whereby you can claim a refund is if it was your main residence and it is sold within 3 years of buying your new property.
Sorry, it's not better news. Please don't forget to rate my answer if I have assisted.