Just a small thing, when you're putting in a clause "subject to finance" make sure you have them write "subject to suitable finance" or something to that effect.
Just to clear this up - in Queensland contracts of sale, this is not necessary as in the Standard Conditions attached to the Contract already states this. Most people write in the Contract (in the finance option) how long they have for the condition, and then under the Lender part "A bank or other financial institution" just to cover themselves.

Hollo - you are more than welcome to ring me to have a chat, I dont' mind. I know how overwhelming it is !!!

Oh and I would think that 21 days for finance approval would be ok - most people go with the standard 14 days - and if it isn't long enough, then extensions of time are the way to go. I had a contract extend up to a MONTH longer for finance approval once, its just risky to ask that if the Seller has another buyer lined up. But in my experience, most sellers say yes because they want the sale to go through.