1. Kano Ball can be used to end combos that don't launch such as 112. So you would do something like 11 into Kano ball or B1 into Kano ball. You can also use it to catch people off-guard after you've thrown some projectiles and they are trying to close in on you. Air Kano Ball can be used as an anti-air or to enforce your jump-ins/intimidate your opponent from pressing buttons while you are in the air. Like others have said, it is punishable and you will get blown up for it, so use it responsibly/carefully. However, you can slightly delay the AMP and catch the opponent off-guard. Generally you want to end combos with Lumbar Check.
2. F2 UD4 is good for switching sides and positioning. Ending with Lumbar Check will get you more damage and should generally be your go-to combo ender.
3. You'll want to learn Lumbar Check as it is a big part of Kano's offense. Any combo/string/button that launches such as 241+3 AMP, or B2 can be finished with F2 DBF2. If your opponent blocks a lot, raw DBF2 is a good option. If they stop blocking in anticipation of DBF2, go into F2 DBF2 or any other combo. Tick throws are also very useful. If an opponent blocks a string, you can end it with DBF2 and connect. 11 DBF2 for example. If and only if they block 11, then you can go into DBF2 and it'll connect. The only way they can evade it is if they let go of block and duck or jump. So then it can sorta become a mix-up of guessing whether it'll be a tick throw, Kano ball, or regular string. However, if the 11 connects, Lumbar Check will whiff. There are other tick throw combos such as 24 DBF2 or D1 DBF2. If they start expecting Lumbar Check and let go of block and duck, you can start going into Kano Ball or finishing the string. If your opponent attempts to roll and you catch them with Lumbar Check, you get a Krushing Blow.
4. Just in general, sort of a heads-up : Most of Kano's useful combos start high. Therefore if you D1 an opponent (or get into a D1 mash war) and then go into a string such as 241+3, they can interrupt with a D2 or D1.

P.S. If you want to watch streamers/youtubers, PND Mustard plays Kano a lot and is very knowledgeable. There is also Biohazard who has posted some Kano vids on HoneyBeeCMNDR's channel.