firstly, the set you're talking about for Soldier includes the Market Gardener, Reserve Shooter, and the Liberty Launcher, even though those weapons do not actually go well together at all
in order to get the Headtaker, you need to kill the Horseless Headless Horsemann with a melee kill on a Halloween map. In casual. You do actually need to get the last hit, otherwise you don't get it. also the Headtaker is just an expensive reskin of the Eyelander that's technically worse because it takes up much more of your screen lmao
the Lollichop is just kinda garbage. it's technically better than Pyro's fire axe, but only because it gives you Pyroland.
there was actually an item set for Sniper with the Sydney Sleeper, the Darwin's Danger Shield, and the Bushwacka. though, it's not that great. i do respect your commitment to helping the team, though.
if you like the Red Tape Recorder, that's fine, but it absolutely sucks at sapping buildings.
at the end of the day, you can play with whatever loadout you want, i get it, wanting to play games without caring about what's technically the 'best' is a nice trait. if you have fun, then play it that way :)
though i do have to recommend going Battle Engie at least once because it's genuinely really fun (Shotgun, Pistol/Wrangler, Gunslinger)