Plumbers are a breed apart. You would think they use gold for soldering your pipes with the prices they charge. My grandfather was a plumber and I trustworthy drain leak repair was on the truck with him at nine years old. A plumber may or may not give you a free estimate. With a little digging, it can be done. Just give them the work if indeed you do buy the house.
Block homes can tell you very quickly if they are stressed out just by the appearance of the mortar joints. Those giant unsettling cracks can and do tell a story. This does happen and mortar cracks maybe 10-years old. You need to investigate further.
It is always a good idea to do some online research. For example, if you have a clogged drain and you live in the Atlanta area you should search for "Atlanta plumbers" or "Atlanta drain local water heater repair service". This will bring up a list of Atlanta plumbers rather than plumbers from across the country.
This is simple, just boil water on the stove, pour and run this hot water on your kitchen sink before you plunge. Do this repeatedly until you unclog the sink.
Make sure that you call a plumber as soon as things start to act up. You will save a lot of money in the long run because you won't be dealing with the damages caused by flooding after the fact. Most people will find that they are not too willing to call in a professional water conditioner early on but it is worth it. It is better to pay someone for a minor issue rather than to try and fix it yourself and end up with a huge mess.
Glycol (Ethylene glycol) is the most common automotive anti-freeze but it requires safe handling. Ethylene glycol is a toxic substance that can cause death if ingested. It also pollutes the environment and should never be dumped in sewers or storm drains. Propylene glycol is a relatively recent alternative to ethylene glycol. It's less toxic but it's still a hazard and should be handled with care. In particular, keep both chemicals away from pets and children. Always dispose according to your local hazardous waste regulations. Don't pollute!
Finally, at the beginning, take the time to get quotes from several plumbers and potentially on non-emergency, lower cost jobs. Get a feel for the plumbing company and see how well they fit with your needs. Meet the plumbers in person. Then, when an emergency plumbing problem arrives, you will have a much better solution when time is of the essence.