Hey

As a quote, usually I'd just ask them several questions about the work they require, unless they've provided you with a brief, or enough details to begin to think how much you think it'll be worth your time.

A quote for me is just a rough estimate on how much the project is going to cost.

Really, you don't need to go into much detail, or at least I don't until the client has agreed to the rough pricing, then go from there..

With the quote..

Simply I'd just calculate how many hours you think it'll take to do the vector work, and then how much you want to be paid per hour. It's no different to the work you've been doing for friends in the past, it just seems different as it's a company, or professional way of doing your work now, instead of the informality.

I'd respond to them telling the process of your work, if you sketch your work first, and then if you get it into Illustrator, and then tell them the prices it'll cost to make adjustments to the vectors, if they need them etc..

Don't be scared on making a quote. They're just looking for a price, and they're probably getting quotes from other people too, to compare.

Just let them know how much it would cost to do what they're asking, they wont be after anything more than that I'd imagine.