With the help of either your realtor or your attorney, as the purchaser you are expected to make the first offer outlining the terms on which you will buy the property you've identified. These tests are normally performed at the buyer's expense, but repairs that need to be performed are usually at the seller's expense. Most contracts have standard language that all customary electrical, plumbing, heating and air conditioning systems are included. Something like a window air conditioner or a portable heater will not be included unless spcifically negotiated. Present your proposal to the sellers.
Most purchase offers usually give two or three days for the seller to consider and respond.
At this stage, you are free to continue to negotiate or to simply walk away. Execute the final contract. The contingency for you reselling your current home, if you own one, is especially important and careful contract drafting is needed. Also consider mortgage services which may not be restricted to just one lender. Get quotes from many different sources and compare.