There is no person, business or other organisation in charge of Bitcoin.
Bitcoin has rules, but these are whatever rules the majority of Bitcoin users choose to follow.
Sometimes people disagree about what the rules should be. Then Bitcoin splits ("forks") into Bitcoin plus some altcoin which goes its separate way.
There are many independent groups of people who have created software that implements the Bitcoin rules. Each group has its own release schedule (or just adhoc releases)
There is one software project with a relatively long history that many people regard as influential. But many others think the software of this project is deficient in some important ways and therefore support other projects.
Many developers of different Bitcoin software pay attention to a public process of suggesting improvements to Bitcoin. This is what results in Bitcoin Improvement Proposals (BIPs). Many BIPs fall by the wayside and are ignored. Others get widespread public acceptance on their perceived merits.
No one deploys Bitcoin software globally. It is up to every person to decide what Bitcoin software they want to use and how often they update it.
When a bug occurs in software, people report it to the software authors using whatever means the authors of that particular software have provided. Each has their own.
If a block doesn't follow the Bitcoin rules it is discarded by all Bitcoin nodes. All full nodes are able to independently and completely verify the correctness of blocks.