Brand Noob, No problems, but have questions

Hi everyone, new to this. I got a Monoprice Maker i3 for Christmas, and have so far completed only the butterfly, a Batman keychain, and a split ring for the keychain. I haven't had any problems yet, but I have a couple of questions if anyone's willing to help...1. How often do I need to re-level the bed? 2. What is the best way to add new filament when one ends? What happens if it runs out when I'm not in the room? 3. Should I remove filament entirely between prints? If yes, do I need to clean extruder each time as well? 4. How often should I anticipate replacing parts, and which parts should I have pre-ordered? 5. Does this model and the slicing file for projects with multiple colors work ok together? Will it stop to allow a filament change as part of the file, for example? Thank you for sharing your experience and knowledge!

you've been watching youtube videos :-) This can be useful - but be aware that most 3d printing you tubers are total anoracks, and not normal people :-)
Yes i include angus.

Questions are not answered in order ;-)

1) no need to preorder any parts - maybe spare nozzles in different sizes. Fun to play with those. 3d printers are generally extremely reliable and don't break often. So wait till something goes wrong - it may never. Before wasting money on things you might never need. Most parts you add to your printers are things you've printed yourself.

2) Before you print something - get a preview from the slicer which will show you how much filament it uses. Make sure you have enough before you start printing and you will NEVER run out of filament during a print. I've got 5 printers, been doing this this for about 6 years - never yet run out of filament during a print. There is no reason for you to either. It's a 2 second check.

3) I tend to leave filament in the machine between prints. Some will have the ends go brittle after a few days to a few weeks. Some won't.
Worst case scenario - it breaks exactly at the point where it goes into the extruder and you spend a half hour or so wondering why there's nothing coming out of the nozzle (me 2 days ago lol)
Also some printers have filament that is fiddlier to change than others. My replicator clones for example. It's round the back facing the wall - real pita - top mounted filament holders are currently on my long term todo list.
At the moment it just gets left until I absolutely need to change the reel.

4) as far as cleaning the extruder goes - pretty much never do that.
UNless you've had a failed print and weren't there so it all solidified around the nozzle (always fun - heat nozzle and pull and scrape it off) - you generally don't need to bother cleaning the nozzle. If you've had filament reel jam (happens when the filament is either tied in a knot on the reel or escapes the reel and wraps round the reel holder) then cleaning the feed cog with a craft knife is also a good idea.

But as far as general maintenance goes - I usually change nozzles every kilometre or so of filament (about 3 rolls) that's if I'm using a brass nozzle.
If you've splurged on a hardened nozzle - then only change if changing nozzle diameter.

If you want to change filament mid print. two ways.
Either pause the print from control panel if printing from sdcard or from the slicer if printing over usb. Change filament and restart.

Or, how I've done it in the past. cut the filament so there's still a few inches left sticking out of the extruder and just feed the new filament in tight behind it.
If the print uses a lot of retractions - go with option 1.

Mind you that said I printed a fidget cube with print in place hinges and no retractions until the unbroken filament had pushed the old broken length through the nozzle. There's no obvious issues with it, and given how many seperated parts of the model there are it's a lot of retractions - so it's not essential.

Thank you!