I'll try and answer some of your questions as a Brit.

Excellent.

We use the term "series" rather than season.

I actually knew that, but decided to use a single term to describe a single thing rather than get caught up in semantics. Thanks for pointing it out, though, as this isn't just for me. Hopefully.

Oddly, the series that seem to be short are the comedy shows that have since been exported to the US (Coupling, Men Behaving Badly etc).

By exported, do you mean shown on US TV, or revamped for US TV? If the latter (and even if not, really), it's always amused me that the US versions outstrip the British versions very quickly, not in quality (necessarily), but in volume. For example, Showtime is showing a version of Queer as Folk. They decided to copy the storylines from the British version (apparently -- I haven't seen the original), but ran out of episodes before the first season was over. Heh.

BBC2 is the more high-brow specialist channel.

So BBC2 shows totally separate programming from BBC1? I thought I'd heard that there was overlap. (In particular, I thought I remembered someone commenting on how Buffy the Vampire Slayer was shown at a reasonable time on one channel, but early in the morning on another.) Also, does highbrow mean more literary things, like, for example, the Pride and Prejudice series done a few years back?

we have hundreds of other channels that are only carried on the new digital platforms

Are these the same sort of cable channels we have in the US, like MTV, the Comedy Channel, Nick-at-Nite, SciFi channel, etc., or are they British based channels?

I think this operates in a similar way to the US networks in that there are only certain periods in the day when they get to show different shows.

That sounds kinda opposite to US networks, who have only certain hours when they're required to show network programming, probably seven hours a day, tops.

I always struggle in the US to work out when shows are actually on...

Heh. Me, too. It helps that we have all those local affilitates throughout the country rebroadcasting the original transmission. Being on the east coast makes it easy. The west coast is as easy. In the Central time zone (1 hour removed from the east coast), shows are generally shown at the same exact time as on the east coast, which means their national programming runs 1 hour earlier on the clock, so prime time runs from 7-10PM for them. In the mountain time zone (1 hour removed from the west coast in the other direction), shows get shown at the exact same time as on the west coast, so their clocks read 9PM-12M for prime time. I'm still at a loss for Alaska and Hawaii. Doug's explained Alaska before to some extent, but it's apparently a little haphazard.

... commercials ...

I'd been under the impression lately that the BBC had resorted to commercials. I guess that was a misconception based on scant evidence.

The adverts are shorter (and typically higher quality) than US adverts

Shorter? Most US commercials are 30s or 15s, at about a 2:1 ratio. How much sorter can you feasibly get?