(Moderators - please move if this is the wrong place, I didn't see a board for Monoprice).

Hi board! I am new to 3D printing. I think I am going to receive a Monoprice Select Mini tomorrow, so am doing my research.
There are a number of mods that it seems people recommend to this printer, and I am trying to sort through the ones that are needed and why. If you have experience in these, i would appreciate feedback.

Here are the ones I understand:
* Heated Bed Cable re-route - This seems to be the most critical / essential mod that has to be done as OOB the cable will fray and break.
* Front Button - mostly cosmetic, but very easy to do and makes the button easier to press. I get that.
* Filament Spool - mainly to rotate the spool so it's not parallel to the printer - assists with making sure the filament doesn't get twisted up during feed. Again, I understand this one.

Now we get to the ones I am less sure about:
* replace the extruder assembly at the top - from what I can tell, this is because the little lever there may break? Is this essential early on? Or can I do it later?
* add a fan to the extruder hot end - explain to me why I need a fan there? It works without it, so what does the extra cooling do? Wouldn't I want this to be hot so the filament is properly melted? There are no electronic components to really go bad here.
* add a fan to the mother board chassis - again, why is this necessary? Are people being overly cautious or is this a real problem? What does it do for me?
* Add stabilizers to the Z axis (?) rods. Forgive me if I have the incorrect axis - talking about the ones that it goes up/down on. Again, why is this needed? What's it give me? Not that stability is bad, but why is it necessary to reinforce those and how important is it?

I think that covers most of what I don't understand. The other mods are mostly cosmetic (adding a webcam, light, tool holder, etc). Any other mods that I am missing which I need to think about early on or can they wait? Seems like so much work for a ready to go printer. :-)

Thank you for any assistance!