the robot standard and giant files (there also is a gatebot one for mannhattan, but thats not recommended for beginners). both are in the gcf files. You might be unable to directly open them and might need something like gcfscape. If im right they are directly next to the example popfile in the popfile list, maybe a folder up (the same folder as where all missions are placed).
Since i already wanted to make such guide but never bothered to im made a quick one that at least should get you going into understanding what a popfile does:
http://tf2maps.net/threads/a-short-guide-to-explain-popfiles-requires-example-pop.28298/
I'd just use mvm.tf . It's actually not that hard, and I've never heard of it creating a "big mess", as you put it.
Its because you cant read the popfile contents. mvm.tf is known to add alot of attributes and templates that arent used or are already defined earlier. This part is a mess in reading and worse when debugging. Your popfile wouldnt update properly once valve updates theirs. in some cases breaking the mission. Good luck finding the bug when mvm.tf cant even read your popfile anymore as it broke with it once they update it, or maybe it generates broken files. Its unreliable.
Most popfile makers will instantly close and delete your popfile once noticing its from mvm.tf. They wont even bother fixing your mess.
If you want to make a good mission, knowing what you do is a must. And understanding the popfile itself is a key part. mvm.tf isnt even failproof against deadlocks, doesnt let you learn anything about what certain attributes do.
mvm.tf is the same as trying to create a map in hammer using sketchup and porting that file directly. It can be used for a quick mockup, but it NEVER should be the final file for the mission or even the first alpha ment for playing.