The term you’re looking for is “bluray authoring”.
Search for that. Industry tends to use Scenarist but it would be too expensive for an individual and they probably wouldn’t sell to you anyways. There are semi-pro tools, most paid, some hundreds of Euros.
Edit: here’s a list of some of the better ones with prices: https://www.videohelp.com/software/sections/authoring-bd-hd-dvd
Not really. This requires a sophisticated attacker. I’d suggest updating soon but I doubt most people are at risk. As always verify downloads before running them and check where you should be getting updates and if you’re sent to a sketchy file host try to find updates from the official website instead.
The biggest risk is MTM interception and replacement of the python executable if you try and use the search tool for the first time. I suppose avoid doing that until you update the client from their website.