What are chunks, samples and frames when using pyaudio

After going through the documentation of pyaudio and reading some other articles on the web, I am confused if my understanding is correct.

This is the code for audio recording found on pyaudio's site:

import pyaudio
import wave

CHUNK = 1024
FORMAT = pyaudio.paInt16
CHANNELS = 2
RATE = 44100
RECORD_SECONDS = 5
WAVE_OUTPUT_FILENAME = "output.wav"

p = pyaudio.PyAudio()

stream = p.open(format=FORMAT,
                channels=CHANNELS,
                rate=RATE,
                input=True,
                frames_per_buffer=CHUNK)

print("* recording")

frames = []

for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    frames.append(data)

print("* done recording")

stream.stop_stream()
stream.close()
p.terminate()

and if I add these lines then I am able to play whatever I recorded:

play=pyaudio.PyAudio()
stream_play=play.open(format=FORMAT,
                      channels=CHANNELS,
                      rate=RATE,
                      output=True)
for data in frames: 
    stream_play.write(data)
stream_play.stop_stream()
stream_play.close()
play.terminate()

1. "RATE" is the number of samples collected per second.
2. "CHUNK" is the number of frames in the buffer.
3. Each frame will have 2 samples as "CHANNELS=2".
4. Size of each sample is 2 bytes, calculated using the function: pyaudio.get_sample_size(pyaudio.paInt16).
5. Therefore size of each frame is 4 bytes.
6. In the "frames" list, size of each element must be 1024*4 bytes, for example, size of frames[0] must be 4096 bytes. However, sys.getsizeof(frames[0]) returns 4133, but len(frames[0]) returns 4096.
7. for loop executes int(RATE / CHUNK * RECORD_SECONDS) times, I cant understand why. Here is the same question answered by "Ruben Sanchez" but I cant be sure if its correct as he says CHUNK=bytes. And according to his explanation, it must be int(RATE / (CHUNK*2) * RECORD_SECONDS) as (CHUNK*2) is the number of samples read in buffer with each iteration.
8. Finally when I write print frames[0], it prints gibberish as it tries to treat the string to be ASCII encoded which it is not, it is just a stream of bytes. So how do I print this stream of bytes in hexadecimal using struct module? And if later, I change each of the hexadecimal value with values of my choice, will it still produce a playable sound?

Whatever I wrote above was my understanding of the things and many of them maybe wrong.