Epson is generally one of the best models under $3,000 on the market with their 5050UB. The previous model, the 5040UB had a power supply issue that plagued a number of owners. Many were covered under warranty, some were not. This has not presented itself as an issue on the 5050 models from what I understand.
If $3,000 is too much, then I might consider the BenQ 3550 which is a very reliable, but more entry level model, than the Epson. It is also known for high reliability.
Not every projector will last for 10+ years without issue. Fans and other electronics internally are subject to issues over the years. Sometimes they seem to last forever, and go through multiple lamps without problems, and sometimes they don't. So, a guarantee of high reliability is impossible. Kind of like buying a car. You can buy from Honda, but that doesn't mean that Honda you get will be without issue, even if, as a whole, Honda has higher reliability. Higher doesn't mean perfect. Same with projectors.
Likewise, just because your friend had an issue with her Epson, doesn't mean you will. Especially with a newer model.
For HDMI, you will want to run at least one, if not two, fiber HDMI cables which you test before installation as to be working with 4K content. RUIPRO or similar is a decent choice. Definitely plan on upgrading/replacing the cables at some point in the future.
You can certainly put Ethernet in place if you want. Running a quality cat-6 cable is a good thing to do. But, true 18Gb/s HDMI extenders are expensive and don't always work if you try to get them on a budget. HDMI cables are still far more reliable and predictable.