I'm glad that a long response was helpful!
I'd say yes, definitely, my masters has only helped. The Masters degree was mostly a 'I might as well do it, I'm a home student so it's free', as if I left and did it anywhere else, I'd need to pay (which is something I or my family cannot afford). Obviously, this goes for any masters degree you might receive but, in my final assessment centre before I got my grad job offer, I was the only candidate with a Masters degree and I feel like that might have given me an edge over others (obviously, my performance factored into it probably as well, but I cannot deny that it may have made a difference). The curriculum in the Durham integrated masters is a bit of a hit or miss imo (I don't like a lot of modules, while some I liked quite a lot), so it really depends on the person - a lot of my friends graduated in third year and moved onto grad jobs, masters degrees in other unis or PhDs as well, but I 100% know I'd hate a PhD so I'm very happy to gain the upper hand over others when competing for positions by doing a masters in a uni I already know, where everyone knows who I am as well. I'm also pretty sure that on average, masters degrees result in higher earnings over a person's life than a bachelors, but I'd recommend having a look online about that and taking that with a grain of salt. But yes, I definitely think that a masters is a great way of standing out when applying for jobs, as most end up finishing with a bachelors. In addition, I feel like a masters has let me become more focused and mature over my last year, as it is much harder than a 3rd year but gives me much more time to organise myself in, than filling my schedule with contact hours and not giving me a choice. Most of my friends having left also has given me space to breathe and focus on finishing my degree as best as I can, since third year can feel super busy on all fronts (and also, gave me breathing room in third year since it was not my last year, and any mistakes I made I could still correct this year!).
Internships in first year are extremely hard to get. I didn't apply in my first year (since I was terrible at coding lmao) but I don't regret it at all. However, I do know a friend currently in his first year who is having a tough time applying because the interviews and application cycles are similarly demanding to actual grad schemes (which is super scary if you ask me). Unless you're an absolute coding whiz or have loads of luck, it's best to save your efforts for second year, which is when most people get an internship (or at least many in my year did!). Spend first year enjoying your degree, figuring out what you like and then aim for stuff in second year having practiced/made projects that will make you stand out. Also, once you get to uni, make a LinkedIn if you have not already, and make sure to keep your CV up to date 🙂 it will help you out later!
You could alternatively apply for spring weeks, which many banks put out for first years around easter, which are little taster experiences usually in fintech designed for people who haven't coded as much as needed for the internships - they are still super competitive, but it probably won't hurt to apply for them!
About hackathons - the Durhacks are primarily made to have a very open environment. You absolutely do not need to be a great, or even good, coder. My first and second durhacks were very much 'let me have a stab at it' and whenever they advertise their free tickets, it's always underlined by 'we are open to attendees with all or none of the coding experience'. I actually happened to win in a category once, when I was still a relatively poor coder - but I got myself into a brilliant team and had some really good ideas which I put my full effort into working towards! It's just a really fun allnighter with the opportunity of working on something great, both to appeal to companies but also to test your own skills against very open challenges.
Yeah, although a lot of Durham students go to Amazon (I think, at least - you can easily verify by checking Linkedin, but I know a few), fintech is a much larger presence in the uni. If you're starting a project with AI THIS early, then you'll surely enjoy the degree and the amount of different spins it puts on AI and adjacent fields. It will also definitely help with catching the attention of recruiters once you're in the application cycle.
I'd love to as well! I'm not sure if Student Room has a PM feature, but if it does, I will send you a link to my profile. It's been lovely talking to you and I hope this has helped you out make a good choice!