New build B650M-HDV/M.2 and Ryzen 7 9700X

1. Yes. That new 105W TDP setting is actually for 9700X because its default is 65W and people were complaining about it leaving performance on the table.
2. 7000-series and 9000-series have the same IOD (IO Die), which contains the memory controller. So there shouldn't be any compatibility differences, barring firmware bugs.
3. Motherboard manufacturers don't bother testing every RAM kits on the market. RAM kit manufacturers can also swap components without changing product names, so these things are just a "suggestion," as far as I'm concerned.

I'm extremely particular about RAM reliability, so I never buy these non-JEDEC "gaming" memory. I only buy JEDEC spec (unbuffered) ECC memory, like this one:

https://www.crucial.com/memory/server-ddr5/MTC10C1084S1EC56BR

Yes, it's only 5600MT/s and with horrible(?) CAS Latency of 46, but I don't care.
No, I'm not telling anyone to buy them. Almost everyone buys "gaming" memory. I know I'm the odd one out.

NVMe has been around for so long, any brand-name (and most non-brand-name) NVMe drives are all fine these days. Again injecting my opinion, I stopped buying Samsung SSDs after 970PRO days, because they switched away from 2-bits per cell to 3-bits per cell for their "PRO" models, completely eliminating the differentiating factor.

Samsung continues to charge more money for their SSDs based on brand recognition from the past, as none of their products have anything particularly special these days.

My go-to SSD brand these days is SK Hynix (P31 and P41), as they're just as fast as equivalent Samsung models, if not faster, and are more power efficient. I also like Crucial, as you KNOW you're getting Micron NAND chips. Buying SK Hynix SSD also means you KNOW you're getting SK Hynix NAND chips. You can say the same about Samsung, as they'd be using their own Samsung NAND chips, but again, no reason to pay extra for them. The only other things I watch out for are 1) 3-bits per cell and 2) DRAM buffer. I don't buy DRAM-less SSDs, if I can avoid it.

As for your cooler, assuming you kept the AM5 compatible mounting parts, I don't see any reason why it wouldn't work for you, even at 105W TDP setting.

Regarding the compatibility of the cooler with the AM5 socket, I have all the factory parts of the cooler.
It is surprising that the cooler was purchased before the AM5 socket existed, and it is still compatible with the existing parts. Just downloaded the new User Manual from the manufacturer's website.