Hey
how can i check or calculate ETH / BTC / USDT fee for transfering from trust wallet to another wallet ?
You can use this
https://etherscan.io/gastrackeris there any specific rule how this fee calculated ?
The fees calculated by the average fees from all of transactions that already confirmed by the block or miners. That will create a standard transactions fees that must be followed by all of transactions that wanna be confirmed by the block.
is transferring from trustwallet to trustwallet (internal transfer) free ?
Im sure if it's not free coz it was moving from one to the another address. this is not a centralized entity that let you switch from one to the another wallet.
or any wallet that have internal (free) option?
It must be centralized and there are no wallets like that. If you wanna get it and store your fund on cex.
is there a difference between BTC address? some one told me that new BTC address has cheaper fee when we want to transfer BTC tho them.
Yes and that's segiwt address. BTC is far cheaper than ethereum right now.