You cannot select seats at the Etihad website - as long as the journey is ticketed you can do it over the phone with no issue or you could download the mobile application and use that

What is the routing and what is the class? Assuming this is purely an Etihad journey then the allowances will be as per https://m.etihad.com/en/information/...on/allowances/ , which is unlikely to be zero ; the excess baggage fees are listed at https://www.etihad.com/en/before-you...mation/excess/

If you are travelling in business or 1st class , then you will get lounge access