Re: length of braided steel toilet hose
As the others have said, you can use pretty much whatever kind of hose you want. For the record, I've seen more split solid tubing supplies than I have hoses of any kind, so it's really a matter of checking things periodically to make sure they're in serviceable condition.
In answer to your question, the length of hose doesn't really matter, just as long as there is no tension on the couplings and the hose is not kinked. IMHO, a little longer is better. A mild "S" curve is fine, a full loop is ok too, keep in mind that longer hoses cost more, so excessive length should be avoided.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!