There is no rule as to who should send the contract. any one party can make a offer. if that offer is agreed upon then it becomes an agreement if there is intent to make such agreement legally enforceable then it becomes a contract enforceable by law.
if however the initial offer is not completely satisfactory then the other side might send in some modified offer which is called the counter offer and the same procedure follows.
There is no hard and fast rule about the location of the date but normally such a date is mentioned at the beginning. Verbal agreements without dates can also be enforceable contracts as long as there is evidence to show that such verbal agreement was achieved between parties. But it is advisable to get everything in writing.
There is no procedure of verifying such address and all but as long as one can prove that the party agreed to contract with such contract is enforceable in law unless it is void by other laws. for example one cannot contract with another to do something patently illegal like gambling or theft etc etc. it must be a legal objective.
certain conveyance deeds require witnesses but not all contracts.
scan copy or xerox copy does not matter as long as the signature is genuine and reflects either offer or acceptance.
one does not need to contract on court paper but certain contracts require stamp papers and registration charges and even notarization.
as long as the intent to contract can be proved the paper involved does not matter. but people use stamp papers and legal papers to imply thats it was done with the intent of it to be enforceable by a competent court of law,
always keep two original copies for yourselves. get prints or copies for the rest of the work.