What are the advantages and disadvantages between staying in the low, middle and high floors? And what should be taken into consideration for the surrounding environment?

Frankly, if you're able to, take the time to visit the different apartments at different times of the day and night to compare.

I say this because generalisations don't always work. Apartments facing busy roads, expressways or mrt tracks may be noisier on the upper floors as opposed to the ground floor. Nowadays, some HDB areas have pavilions for social gatherings, but these pavilions cause loud echos when people use them. Etc etc.

Best thing to do is to make the time to visit and take a look for yourself.

Low floor: noisy from void deck, carpark and roads. Also, anything drop from above floors sure hit, like dripping wet clothes, cigarettes, rubbish.

Middle floor similar to low floor depending on which middle.

High floor: Good scenery, windy, good to feel natural wind. 1 bad thing is if lift breakdown, good luck to climbing stairs.