try to get the seller's lawyer's contact, and try to talk to the seller's lawyer.....(which i did for my case)

first, get your letter of offer from the bank first to ensure you secure your loan (to reduce risk of losing the 10% deposit)
then, sign s&p
signing of loan agreement comes after this

signing of s&p should happen two weeks from the time you paid the booking fee

if you are using the same s&p lawyer and loan lawyer, you can sign both at the same time

you can state in the s&p tat if vendors fail to provide all the necessary documents, vendor bear the legal fees and all other charges (but it will depend if vendor would like the clause there)

yes, you can pre-sign, which i did for my case, because it is almost standard and i was sure that i was going to use the same lawyer as my s&p (which was a stupid choice)