taxable value

As per Section 15 of CGST Act 2017, The value of a supply of goods or services or both shall be the transaction value, which is the price actually paid or payable for the said supply of goods or services or both where the supplier and the recipient of the supply are not related and the price is the sole consideration for the supply.

Read section 15 of CGST act 2017 for more details.

Yes, Frieght amount needs to be included in the taxable value.

you want me to refer section 15(2)(a)(b) Or any other Sub Section

its called Composite Supply

read section 15(1),(2),(3),(4) and(5) . So that you will get to know how to arrive the assesable value.

It's is your choice for based on your nature of Business...
In case you are transport business dealer then you can create separate invoice...
If not you ll be add your transport / freight charges in your bill then it ll composite supply.
If it's composite supply then you ll be calculate tax in freight as per principle supplies...