Shoud I buy OLED ?

So, I’ve been using a 1080p VA screen for years now (ASUS VG248QE 144Hz), and my second monitor is an old AOC D2367PG IPS. I really want to upgrade now (I still love it, but there’s a vertical dead stripe).

1. Is OLED safe in 2025? (in terms of burn-in and all that)
2. Is a 4070 Super good enough for QHD? (no way I’m going back to 60Hz)
3. I'm planning to buy a Xeneon 27" 240Hz OLED
4. I’m a bit worried that QHD might become outdated soon with frame generation and everything — should I go 4K instead?
5. I can’t decide between a 16:9 OLED or a 21:9 ultrawide. I love OLED, but ultrawide looks so cool too. What are your thoughts?