How many roads in a hood would you say would be considered
a) a tiny hood
b) a small hood
c) a medium hood
d) a large hood
e) a gigantic hood

Rangin in numbers of 2 roads to 20 (or more if you think so) roads.

number of squares roads take up? or number of lines/segments/etc roads make? or something else?

I would say it all depends on the space between the roads, and how many lots you can fill up. Personally, I'd say that a tiny hood would be best described as a single road with 2 or 3 little streets or bays that spawn off of it. From there, I'd say that the number of streets could grow from 4-5 for a small hood, 6-7 for a medium hood, 9-15 for a large hood, and anything over 20 for a gigantic hood.

Whether you need a camera hack or not. Large and gigantic hoods require camera hacks to see all the space. Other than that, I don't have any idea.

I create all my hoods in SC4, and the question doesn't really make any sense. I can have a flat map with two roads going from one horizon to the other. I can put many, many lots along those roads or just a few. Number of roads doesn't matter. Camera hack probably doesn't matter either if I have just half a dozen lots scattered down those two long roads but it's more meaningful than the number of roads. You have to decide what's gigantic - is it terrain, number of lots, number of roads, combination of all three? Smallish map with small number of roads perhaps?

Can't answer the question, but I really hate small hoods since all my sims have a truckload of kids.

Instead of number of roads, I think of how many lots I intend the neighborhood to have. If I think there will be many playables at some point, it would make sense to use one of the terrains with more streets (ex., Belladonna Cove, the Downtown map). If it's supposed to remain small, maybe something like Straight Plains is in order.

As far as classifications (and these are just my thoughts on them):

A "tiny" neighborhood might have one or two lots and 2-8 playables, similar to a ranch in the literal middle of nowhere. It'd probably use the previously mentioned Straight Plains map without anything attached to it and created without townies of any kind. If I attach a Downtown (only EP I have), I write that it's considered hours away.

A "small" neighborhood might have 4-12 playables and a community lot or two. Sedona is the first one that comes to mind.

"Medium" I'd associate with several of the Maxis neighborhoods (Strangetown, Veronaville).

"Large" would be Belladonna Cove (yes, another Maxis neighborhood example).

"Gigantic" would be something larger than I could create (read: large base neighborhood map, downtown, college, business district, etc., attached).