Too much loudness over dynamics means your ear will fatigate faster and your brain might get bored easier, thats why so much people prefer the sound of the 60s and 70s when the music had more dynamic. People get tired easier of new POP or ROCK music productions and rock oldies its still being heard.
I will master your song in 2 days, I prefer to check out my work in the morning a second time because thats when the ears are more fresh and rested...
The frequency response shown means that my room is perfect for mastering
The quality depends, for the basic gig you will get a basic mastering.
I will need the song with this characteristics:
-The song should be .wav or .aiff
-The mix should have a headroom between -3db and -6db
-If the mix is 24 bit/ 48,000Hz even better, but 16 bit/44,100 Hz works just fine
- 2 songs as a reference, a guide you want to sound like
Mastering is not magic, it depends on the quality of the recording and the quality of the Mix.