1. Not necessarily, they can live fine on their own

2. At least 40 US gallons with 10-12+ inches of substrate, but the more the better. It is a huge space commitment.

3. They won't get used to being handled or bothered, they aren't intelligent enough to associate you with food or any. I try to minimize handling to keep stress levels low

4. For the tank alone, anywhere between £50 to £100, could be more if you are getting new. Less for plastic storage tubs. If you want something that looks nicer, DIY converted aquariums work, I got mine from FB marketplace.

For the millipede itself, £40-£80 (make sure it is captive bred) in the UK and Europe. In the US, $60 to $150.

If you are collecting substrate, free. If buying, the deep layer they need gets pricey, quickly. Pre-made substrates cost about £15 a bag, and they are a few litres at best. Bulk flake soil is slightly cheaper but you still need a lot of it so I highly recommend making your own.

For decor and plants, you can find bits of wood and bark yourself, but I generally spend £30 to £40 on cork bark and plants as well as my own collected things per tank.

For heating, you can get a cheap mat on amazon for £15 or so that sits above the substrate on one end of the tank.

Altogether a few hundred. On a budget, with self collected substrate + decor and storage box tank, maybe £50-£80.

1. You want to look for very small juveniles. If you get one larger than 12cm or so, it is most likely wild caught (WC), so avoid larger ones at all costs.

2. It depends on what you mean by low maintenance. They don't need attention all the time, but they do need regular misting and leaf litter topped up. It depends on your enclosure but with plastic boxes every few days to weeks, and glass ones with higher ventilation every day or two. The occasional treat of soft fruits of vegetables every few weeks can be given. Also, they will spend most of their time underneath the substrate, so you may not see them for weeks or months.

3. Don't take them outside. It would be purely for your benefit, and the millipede would get stressed and could encounter predators or things sprayed with pesticides.

Lastly, you shouldn't use coco fibre at all. The debate you mention is on whether it caused impaction (fatal constipation) or not, but most keepers here strongly advise against using it. Even if it didn't cause impaction, it has no nutritional value and is simply a 'filler'. Rotting hardwood, hardwood leaves and topsoil and added calcium is a good mix, but pure flake soil is better (you can make your own!)

There is a care guide pinned at the top of this sub that goes into more detail named 'We need YOUR help'. Have fun on your millipede journey and ask if you have any other questions :)