Import tariffs & Sales tax

Hello,

My company is located in Hong Kong and trading with high end jewellery.
Currently considering to sell the products in the US.
The goods would be imported and then sold online via the plattforms for these type of goods.

Following questions:
Are the import tariffs in every state the same or do they differ?
Are there certain states (e.g. Alaska, Delaware, Montana, New Hampshire and Oregon) better for online sales/mail order business, due to lower taxation and no sales tax?
Is the sales tax of the state of the seller or the buyer relevant, if it is an online purchase and shipped by special courier to the buyer?

In order to have most competitive sales prices in the market:
Does it make sense to import goods via a company in one state to benefit from lower import tariffs, which sells the goods to the company, located in another state with lower sales tax?

What is the common company form choosen for import/online sales in the USA?

If you can recommend any consultant for these types of questions, welcome to get the contact details!

Looking forward to your reply.