I was thinking the same thing. First off, whenever someone says "trust me," as a rule of thumb, don't. His advice sounds really self-serving. Trustworthy people are always open to committing in writing or in ways that don't require so much trust.
Now, the dude who wrote the cover letter doesn't seem all that stupid to me. Sure, the writing isn't great, but for all you know English is his second language. I'm not so sure about his hacking skills, though (CSS?). I'd still interview him.
CSS is very difficult in the sense that implementations vary so wildly, and browsers demonstrate random bugs where you least expect it. Oodles of experience counts for a lot.
I was going to say the same thing. "We'll take care of you" is simply not a promise that startups can make. You might work your ass for them for a year at a below market salary, only to see the whole thing tank.
True, or to be laid off if you're considered 'too greedy'.
Let's not forget your employers had this great idea and you should be happy to be honoured to contribute to that great idea. After all, you're jut a code monkey.
Surely this is what stock options are for?