New PC, no GPU - Cooling and quietness?

[ClassicCar]

Good evening,

I have settled on a build for a workstation PC, but the choice of a case is proving oddly difficult - largely because I have no concept of required size and cooling requirement. The simple build is as follows;

CPU: Intel Core i5-12400 2.5 GHz 6-Core Processor
CPU Cooler: *Thermalright Assassin Spirit V2 66.17 CFM CPU Cooler
Motherboard: ASRock B760M Pro RS/D4 WiFi Micro ATX LGA1700 Motherboard
Memory: Crucial Pro 32 GB (2 x 16 GB) DDR4-3200 CL22 Memory
Storage: Western Digital WD_Black SN850X 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
Power Supply: Phanteks AMP 650 W 80+ Gold Certified Fully Modular ATX Power Supply

I'd be grateful if anyone could answer a couple of questions;

1. The motherboard is Micro ATX - but will the PSU (being listed as 'ATX') fit in a micro ATX case?
2. Regarding fans and cooling - is it the norm to swap out case fans? Is there a rule of thumb as to how many case fans are required?
3. Could anyone please suggest a very quiet case of an appropriate size, for up to £65 or so?

Many thanks.