Estimate a freelance project quote from scope.
A quote is labour plus contingency plus the costs you will pass through. Contingency is applied to labour only, because expenses are already known amounts and padding them is hard to defend. A deposit of about a third covers the early work and filters out clients who were never going to pay, which is why it is shown as part of the quote structure.
Project quote
Quote = hours x rate x (1 + contingency/100) + pass-through expenses; deposit = quote x 30%
Generally no. Expenses are usually known or capped, and padding them invites scrutiny that undermines the rest of the quote.
A quarter to a third is standard for project work. It should at least cover the effort before the first deliverable.
Quoting a fixed total keeps the conversation on scope and outcome rather than on hours, though some clients require a rate breakdown for procurement.