Power Steering Question, Flush fluid first or replacing pump & hose first?

Hello yall, my 2012 with almost 274k miles needs some maintenance over the power steering system. The pump is going out, and it has some leaks. I just like to get some ideas before I start fixing it.

- I got the truck used, the previous owner filled it with clear power steering fluid, type unknown, I assume it's dot 3. I'd like to change it back to the atf fluid according to manual with a flush
- Power steering pump needs to be replaced, a remanufactured part is on my shelf ready to go
- Cooler to reservoir line is leaking, I'm looking at the Gates oil cooler hose 3/8 inch hose as a replacement, since toyota doesn't just sell the hose itself, they just want to charge the whole cooler assembly for $$.
- Also bought a reservoir to pump hose as preventative maintenance since I got a brand new OEM one for cheap

Here are four things I's like to do, just really have no idea if should I start replacing parts first or should I flush the fluids first? What do yall think?

Thanks in advance! My ears open to all suggestions