Once you have selected your property and had your offer accepted by the sellor, the process should not take more than 6 weeks, if you will need bank finance, then it will take a few weeks longer depending on the speed of the banks.
If you really do not want to lose the property, then make sure that the contract is fair and that there is no unreasonable risk. It is best if your legal advisor checks all documents before signature. Theymight be trying to pressure but might also be telling the truth.
Standard practice means that you will sign a furture sale contract in case of mortgage, in the case of a 100% equity purchase than you can directly conclude the sales contracts.
The future contract should contain the agreed final version of the sale contract.
To an escrow account in accordance with the escrow agreement which mirrors the payment terms of the sales agreements.
Usually about 6 weeks.
In Prague it takes approximately 1 month.