Question Fees for hommormophic assets

holla. i have one question. how the fee is paid for hommormophic assets? are the fees paid in dero ? how are subtracted ? what if one account has only this hommormophic asset ? how is the ring kept safe without revealing the sender ?

what is registration transaction ? does a user first need to register his account ?

i am thinking of making a smart contract bringing erc20 tokes on dero via smart contracts but i don’t understand how the fee is paid for hommormophic assets. thx

can ico be created ? like hommormophic conversion rate. send xyz dero then user gets conversation_rate * xyz ? is this possible ?