I'm assuming that the filter in your tank is the same as in my Juwel Rio? That was a big black box in the corner, white plastic holders and square sponges about 2 inches thick.
The water in the Juwel filters is pulled down through the sponges, then pumped back up through that internal tube thing then out through the little tube you attach through the hole in the side. The sponges are loaded into the white plasic holders and lowered into the black box. So at the bottom you put the fine blue sponge(s), on top go the coarse blue sponge(s) (different size tanks get different numbers of these, but the principle is the same). Then you're supposed to put the green nitrate sponge, if you have one, and the black carbon sponge. Leave these out, you don't need them, you'll put your biorb filter here. Then lastly the white pad. Fill the bottom holder first and put it into the box, then the second holder with the remaining sponges and the plastic cover on top.
When your ready to put your old filter pad in there, switch off the pump and lift off the plasic cover. Then just lift off the white pad, put your biorb pad in and put the white pad on top of it. You don't need to remove the holders to do this. When you clean the filter pads in a few weeks time, you'll have to lift the pump out (I always found this a fiddle!) so you can get the plastic holders and sponges out, but you shouldn't need to now (unless your hands are too big to fit!!).
As for the water, I just boil a kettle to get the water temp right in the bucket when I do a water change. Some people use hot water straight from the tap, but if you have a hot water tank that fills from a storage tank in the attic like I do, you never know what's got into the water!
Edit Just seen your last post. That little pipe can be turned to point the water flow in the direction you want. It doesn't have to be out of the water. It should be adjusted to ripple the surface of the water, but not so much that it causes a tidal wave. If your fish prefer calmer water, point it at the back wall.