Raindog, yes, smaller spiders stay in smaller containers. It's safer to keep them this way as its easier to keep an eye on them, monitor conditions, and feed them. Too big of a container and it would be too difficult to feed such a small spider. So along the way, their enclosures will get upgraded as they increase in size. Typically, small slings are kept in apothecary dram vials or condiment type containers. The acrylic boxes I have are nice for larger slings and juvies. I actually need to rehouse my OBT soon as she is getting a bit snug in there. Hoping that someone will be selling some acrylic enclosures at the next reptile show here. And of course a larger enclosure is for their permanent setup.
Most tarantulas are kept as singles as they are cannibalistic and will eat anything that they can successfully overpower. Heck, even breeding tarantulas can be quite an ordeal because many females will eat their male! I only know of a handful of species that are able to be kept communally.
As for handling, most species can be stereotyped into whether they are docile or defensive and general attitude and behavior, but of course there are exceptions to every rule. I haven't really handled my T's too much right now as most of them are still slings and too small, I'm afraid I would lose them if I took them out. But I do plan on handling them, if they allow me. If not, then that is ok with me too. IMO, handling is on their terms, not mine. And they are still venomous creatures that require focus and respect when being handled. My Acanthoscurria geniculata is my biggest tarantula at about 6", and I would love to handle her, but she is a beast lol. I won't even call her a defensive T, I'd actually say she is aggressive because she won't even bother to threat pose and actively auto-attack anything that enters her lair.