Hi Steve
Can you introduce me to your writer friend, I could do with a friend like that!
Depends what you're planning and how much time you have, but I'd think if you're seriously developing iSpeakers you might want to look into affiliate programs rather than Amazon. Amazon's great if you want something quick, but I've heard that affiliate programs pay better on high-ticket items (like speakers, home theatre, etc). Check out the Affiliates4U forum. Like Acorn, it's a Uk forum full of experienced people who are kind enough to share their experience and expertise. I've started joining some Aff networks and some have very nice widgets and things like comparison shopping functionality that you can add to your site.
IIRC Domainpress lets you export your Wordpress database if you decide to leave them, so you've got nothing to lose. However, I had another look at their site today and the "latest updated" blogs and posts they feature on their homepage look a bit... how can I put this politely.... well, they have a similar consistency to a certain brand of tinned meat! (Not the design/layout but the content). I'd be a bit wary that they could get marked as a "bad neighbourhood" in the future, so keep an eye on it (shame, really, as it's such a great idea)
At the moment I'm looking for affiliate programs for the credit cards site. I think they'll pay better than just the ads. Probably put some unique content on it too, before submitting it to the search engines. I read on one forum (was it this one), that someone Googled for Facebook free advertising vouchers and found a few - that might be worth a try? An SEO buddy tells me FB advertising can be very effective if you're aiming at a market they cover
Yea, the extension debate rages across many forums! I reckon it's becoming less of an issue as people get used to all the new extensions. (plus a lot of users don't know or care what extension they're clicking on - I know that's heresy to say on a domainers forum

) If you're buying the domain as an investment then the extension makes a big difference. If you're buying it to develop a minisite, then the keywords become more of a factor IMHO
Yea the Adwords tool is driving me potty! I spend a couple of hours using it most days. TBH 8,100 sounds more likely for Tokyo hotels, but that's just my guess
Let me know how you get on, whichever option you choose
Cheers, Jon