Hana,
There are several posts about both subjects and lots of YouTube videos about draining and changing the pouch. I plan on doing my own video in the near future and I will post a link.
Personally, I don't do much about the odor other than light a match after I'm done draining/changing. As far as draining my pouch, I always sit on the toilet, I always hold the drainable part upright as not to spill the contents, undo the clips and I fold the opening outward like folding a sleeve. I pinch the opening with my fingers and aim down between my legs and unpinch my fingers. After I get most of the contents out, I take folded tissue paper, fold around the opening, wipe clean, then using the same tissue, swab the inside of the opening. Then I unfold the opening and use the edge of the clip to rake any residue I might have missed back into the pouch.
Changing the pouch, I usually put some folded tissue on the sink in case my stoma starts squirting. I use a washcloth and bar soap. I get the washcloth soapy, and push between the wafer of the pouch and my abdomen, starting at the top and work my way down and around the stoma. Once the pouch is off, I put it to the side and use it to collect tissue I use to clean up and around the stoma. Once I clean the stoma with tissue, I take the soapy cloth and wash all around the area where the wafer sits and my stoma. My stoma tends to bleed a tiny bit but it's no big deal. Then I rinse the washcloth thoroughly and wipe all the soap off of the stoma and skin where the wafer sits. I then take folded tissue and wrap it around the stoma and pat the area dry with a towel. Once dry, I apply skin barrier and then I put the new pouch on. Then, fold the pouch so the opening is pointing upward as to not let anything out until I snap on a clip. I hold my hands down around the left and right sides of the stoma against the pouch for 30 seconds to heat activate the wafer so it creates a good seal. Then I place my hands over and under the stoma for another 30 seconds. Once I'm satisfied the seal is good, I snap on the clips. I use 2 clips in case one fails. I then use a Clorox wipe to clean the sink whether or not my stoma squirts.
You'll get a better visual once I create the video. But this is how I will be doing it in the video. Everyone has their own way. I hope this helps.
Bain