OK well I'll contribute my ideas...
What would be the top 5 things you'd want to cut or change from the books?
1. Helmacrons. And all similarly 'well that was ok/good, but silly' things like the Nartec and the Starfish Incident and the Andalite Toilet. They're just a little too high on camp value for a story about child soldiers. Now, both the Helmacrons and the Nartec gave us some fantastic visuals, things we might like to see in a TV show. It's not inconceivable, however, that one couldn't find a way to work some of those visuals back in.
2. Plots that went NOWHERE. This doesn't mean I'd cut every plot that went nowhere; I'd make them go somewhere, if possible. Like remember when we had reason to be concerned that maybe the Yeerks might have been able to mess with things just a tiny bit on the Andalite homeworld? I would at least make an EMOTIONAL journey of it -- for instance Ax jumping to that conclusion due to his close involvement with the situation, his emotions running high, and only after he does something foolish does he realize that Visser Three has morphs from the Andalite Homeworld because he has the body of an Andalite. An easy conclusion; but not one he was level-headed enough to make when he should have, with the death of his brother and all. It gives Ax a chance to fail a little and make bad mistakes, something that he didn't do a lot, compared to the rest.
3. Visser Three. The further Visser Three stays away, the more of a threat he seems. As an indirect influence, he's more powerful than he is as the Visser Three who is Always Right There. There's only so many times you can temporarily beat or evade him before he stops looking like a threat. Keep him for the BIG moments in Book One, and maybe find another Boss for some of the early books (Chapman? Then Melissa would remain a character!) I LOVED the Visser Three we saw in the Andalite Chronicles and the Hork-Bajir Chronicles, and some of the later books, and even to an extent in Visser. I loved that he was obsessive about Andalites. I loved that he was clever, but it would be his obsession which blinded him in many cases. I loved that he could be subtle. I loved that he wasn't easily defeated. I want more of that Visser Three.
4. A recurring element of the books was the PTSD-related nightmares all the characters had. I love dream sequences in TV, and I love the idea that even at rest, the Animorphs just don't get a break. I think a lot of the weirder, rule-breakinger ideas could be shown in brief dream sequences -- I'm one of those madpeople who actually LIKED elements of the buffahuman book, but it broke rules too much. But the Buffahuman makes fantastic nightmare material! Ditto the idea of being shrunk down to a miniscule size; ditto some of the visuals with the Nartec; maybe even some of the Starfish things could work their way in there.
5. The end. Of course. I'd keep the majority of things, but not the stuff with The One and all that. I think I might have it actually end with Marco and Cassie forcing Jake to try and heal a little by making him morph dolphin like in the books. And I just couldn't drop a bridge unceremoniously on the Auxilliary Animorphs. One or two of them would survive, and HATE the surviving original Animorphs for trying to just sacrifice them like that. I'm sorry, I feel like they only died because K.A. needed a body count but couldn't have Anybody die; so she just wiped out a ton of people in one go rather than kill any 'main characters'.
Would you introduce new plots to replace any cut material, or to give fans of the books some new surprises?
Honestly I'd like to now and then, but mostly I'd stick to book-related stuff. As I said I really like the nightmare element, and I might have a whole episode dealing with that. One thing I realized is that it's basically impossible to work the "we can't tell you who we are" etc element into a TV show where you're showing their faces, their lives, their enemies, their battles, etc. So it might be interesting to have an episode where they try to write journals of what's happening to them, but eventually of course have to destroy these journals.
Do you have any particular people in mind you'd like to cast?
Not really. I do know a guy who I think would make a fantastic Jake.
How long would the show be -- half-hour or an hour?
I really love hour-long shows. The time allows you to get a good balance of action and rest, emotion and motion. I think Dexter, LOST, Sherlock (hour and a half technically), Star Trek, etc. At the same time, hour-long shows discourage a younger audience, which would be a big theoretical problem with this show -- you can describe immense gory violence in print and publish it for a younger audience, but when you put it on screen, it's not appropriate. Even better, longer shows at least in America are generally run on cable or subscription channels, at night, and thus avoid the watershed problem we saw on Sherlock a couple weeks back (there was a big fuss over them showing a naked woman on TV before the watershed).
Originally I'd thought an animated show, in a Serious Anime style, would be ideal. However, if I were being practical about getting this produced, and watched? It really wouldn't be. Thanks, poparena, for explaining this!