1. No spend-based offer or any other kind of voucher based offer other than the stated welcome benefits.
2. It is an Eazydiner membership that comes with the Premier card. When you use the card to pay via Eazydiner, you get 30% off on your total bill over and above whatever discount Eazydiner may itself be offering in that restaurant.
3. The vouchers we receive are the Taj Experience Gift Vouchers, which can be used for any and all spends in Taj Hotels. You can simply ask them to bill all bills to your room and pay your total bill at the end with TEGC vouchers in part or in full. As far as whether the vouchers themselves can be redeemed partially, I don't know. You will have to find out and update here. I only know that the Rs 10,000 Amex TEGC voucher issued as milestone benefit in the Amex Platinum Travel Card has to be redeemed in full. If you redeem it partially, you will forfeit the remaining amount. I don't know whether the terms of use of the voucher issued by HSBC Bank are similar or different than that issued by Amex.
4. The HSBC Bank Premier credit card does not have tie-up with Priority Pass for international lounge access. It has tie-up with Lounge Key. You have to go to this link -
https://www.loungekey.com/HSBCPremierIndia and sign up on the Lounge Key website using your HSBC Premier card details. It will show the number of international lounge visits allowed with the card plus 8 guest visits annually (only for international lounges). For accessing Lounge Key international lounges, you have to show your boarding pass and the Premier Credit Card (primary or add-on card).
5. HSBC Premier card allows up to 3 add-on cards (which come with unlimited domestic and international lounge access) for close family members. Not necessary for the add-on card member to have an account with HSBC Bank. All spends by add-on card members earn points for the primary card holder.