Does anyone know if we can get the following fields on the mentioned records in SuiteQL? 1. shippeddate field on item fulfillment. 2. Remainingamount with field id as amountremainingtotalbox on invoice. 3. unapplied amount with field id as unapplied on credit memo.

You should install Tims SQL tool and just run the query to see if you get back the values you'd expect

Those fields are not present in the transaction record or transaction line table.. But there can be some hidden tables which I am not aware of, have found such insights quite a few times previously.