Replace HDD to SDD; max RAM; clean/or replace fan

Hello Mac People -

As the title states, I am looking to replace the current 500GB HDD with an SDD. I would like to max out the RAM (it currently has 4GB but I had read that 6GB could be installed - if this is possible with this particular iMac, I would like to do that).

And while I have it open, I plan to clean and/or replace the fan - this the main reason I am doing any of this. It’s an old computer and it runs perfectly fine for what I need however after about 10-15 min of doing anything - the fan starts up. It’s loud and didn’t use to do this. The computer is warm to the touch and occasionally it will shut itself down (this is very infrequent but now that I know to watch for it, I have noted that it’s happened in the past - I usually shut the computer down myself and will sometimes have an external fan blowing on the case).

I have never opened an iMac before - so I most likely don’t have all the necessary tools yet. Any direction or recommendation on supplies is greatly appreciated. This is just a pet project and I’d like to keep this iMac going for as long as possible.

Thank you!