Hi Moscow Wolf,
Let me try to answer your questions - with the accent on the "try"!
Buying the "right" property in Bulgaria can be a terrible lottery .. and it is far more complex than you might imagine to do it correctly. Much has been said about the UK people who check their brains into left luggage when they check in at Gatwick.
Getting a structural survey done in Bulgaria is, actually, not a difficult thing. What is difficult is finding the right person to do it. Structural surveyors in Bulgaria are called "Building Engineers".
You main problem comes with the selling agents. Now the real estate market in Bulgaria is a shark-infested area. Estate Agents are not the same as those we have in the UK they are Property Brokers. They agree a price with the seller and then sell it for what they can get ... keeping the difference!
They want to make the process as painless as possible and as easy as possible to get you to buy.
Usually they have some tame builder on hand who will "give you a quote" for what needs doing and for anything you want doing. But the advice they give will almost certainly not cover any serious existing problems which suddenly and mysteriously "appear" after you have bought.
The only answer is to make sure that you do no allow yourself to be rushed into anything (make sure that you allow yourself enough time for the process) and ensure that you have some time to yourself away from the selling agent.
Find yourself an interpreter (your hotel staff should be able to help you with this) and set about finding an independent Building Engineer. You should be able to do this within half a day. The 100 or so Levs that you have to pay the interpreter will be well worth it in the long run.
The 200 Euros you pay to the Building Engineer may save you 2,000 ... or even your sanity!