Oh haha! Well I can link you to the one I usually use when I want to watch something not available in the UK here.
I think Marvel has always been pretty good with character. I think their Phase 1 and 2 had somewhat mixed-to-positive results, but Phase 3 has definitely seen some good work and more and more Feige is trusting the riskier choices directors and writers. I think that's why they at least got an Asian director and Chinese American writer. I think they'd both be aware they have to write a good character. I think they just should think about the right things and leave the things that work.
Exactly, and I think that depending on the tone of the movie like I said either infer or suggest that he is immortal (if it's more of a martial arts espionage spy political thriller) with unreliable information or full on confirm he is (if it has a bit more mystical/spiritual leanings). Either way it makes for a compelling narrative. Imagine a man so powerful and influential that he's convinced his followers and enemies he's immortal.
Read up on all of them a bit and while I think the "same powers/abilities/skills" thing can be seen as played out, I see Cat having the most potential. Razor Fist feels very schlocky kung-fu movie which could work if the film goes for that, but I don't see him as a second in command. Zaran has the MI6 connection but the same thing applies to him also.
Cat's look and style is very cinematic in my opinion. Depict him as a martial artist on par with Shang Chi but uses throwing and combat knives, handguns,, sniper rifles, tech gadgets, anything. Show him as a guy who just mows down MI6 agents like it's nothing and that's why they need Shang.
I also would make his rivalry with Shang a lot more personal. Something like say, Shen Kuei is jealous of Shang Chi because Zheng Zu took in Shen Kuei as a 'secret son' of sorts. No one including Shang Chi and his mother don't know of him, but Zheng Zu raised him to be an assassin/spy and he's his second in command as the top ranking Si-Fan member. So while Shang Chi is Zheng Zu's proud son, his bodyguard/head of security and/or maybe the heir to his father's business, Shen Kuei is 'evil' Zheng Zu's 'secret son' and his right hand assassin. But he is not the true heir as the leader of the Si-Fan as Zheng Zu has made it clear he will bring Shang Chi over to that side and he will take his rightful place. This creates a complex within Shen Kuei's psyche in which he thinks he's better than Shang because he's a representation of Zheng Zu's true nature while Shang represents the facade. And also, he wants to prove himself to Zheng Zu as his true son so he approaches his missions that involve Shang Chi with recklessness, ego and maybe gets increasingly insecure.
Make them true mirror images.