[GroundUrMast]

I'm not one to discourage you from building your own antenna... That said,

I've seen simple indoor antennas such as the RCA ANT-111 offered at the big box home center for about $10. You can easily spend much more than that building your own antenna if you don't have materials laying around.

I'd suggest you try a basic store bought antenna and if needed, a factory built cable to allow you to locate the antenna near a window or any other location that proves to have reliable reception.

To address some of your original questions:

Building penetration loss can vary from single digit to more than 30 dB. The effect on NM is more complex than simple attenuation... Building materials can cause reflections and there are almost always sources of RF interference in a home. These along with the simple reduction in signal level can produce NM reductions that are still greater.

Amplifiers are useful for overcoming loss in cable and splitters, and in some cases, overcoming a poor noise figure in the tuner. Amplifiers do not 'pull' signal from the air, antenna or coax. Amplifiers can only 'push' a copy of what they are fed. So if an amplifier is fed a poor quality signal, it will 'push' a larger version of the low quality signal down the line, just like a water pump will push dirty water if it's supplied that. Amplifiers can be overloaded... If that happens, the output signal will be less usable, perhaps unusable. In your case, the signals shown on your TV Fool report are fairly strong... enough to recommend against using any sort of amplifier (for fear of overloading problems).

The ideal location for an amplifier is at the antenna, before the loss caused by cables and splitters. Preamplifiers are almost always built as two separate units, an outdoor amplifier that can be located at the antenna (in the weather) and a power supply unit that can be located indoors, near an outlet. The power is coupled into the coax run between the indoor and outdoor units.

When signal levels at the antenna are relatively high and there is a long run of cable to the splitter, a distribution amplifier may be appropriate. Most DA's are intended for indoor mounting. Good quality DA's generally can tolerate strong signal levels at their input, but like any amplifier, can be overloaded if the levels are too high.

Antennas with built-in amplification vary in quality... I avoid them. I would rather start with a good antenna that can produce high quality signals at it's terminals ('high quality' is not the same as 'high strength'), then depending on the need, add the appropriate accessories to deliver that hard won signal to the tuner(s).