Adding the water conditioner to the bucket is always the preferable way to go.
I use just a simple flexible pipe to siphon the water out and this is also enough for me to clean my substrate a little each time. I never have 'a lot of debris'.
I also arranged my tank right from the outset to facilitate cleaning, with distinct low points in the substrate and even a small sand 'beach'. Most debris accumulates in these low points.
For pouring the water back in, my tank is 15" tall, with 13" clear water, between the substrate and the water surface. I pour the conditioned water directly AND SLOWLY from my bucket, (which has a handy pouring lip), over the beach. I note that the bubbles formed never hit bottom and I am yet to disturb the sand...though certain fish like to explore the new water coming in.
(In the wild, such bubbles of new water are often associated with new food entering the water).
A method from the Olden Days would have you place a small saucer in the tank, on the substrate and pour your water in over that.
I normally change 16 litres of my 88 litre tank at a time and have not bothered to equalise temperatures. (Remember that, under normal conditions, fresh rainfall isn't pre-warmed
).
When I've done larger water changes, I have added a little hot water from a kettle, just to take the chill off. As you know, water from hot taps comes via copper piping, (or even lead piping in some older properties) and this should be treated before adding to the tank.