Alternately, you can use this tool to generate one:
http://tools.trepmal.com/wp-readme-generator/

A readme.txt is needed so your plugin will display correctly in our repository, but also so we can make sure you're providing the users with all the information they need before they install your plugin. Our goal with this is to make sure everyone knows what they're installing and what they need to do before they install it. No surprises :)

Could you send a link so the completed plugin can be downloaded please. Alternately you can reply to this and send a .zip or .rar file.

Alternately, you can use this tool to generate one:
http://tools.trepmal.com/wp-readme-generator/

A readme.txt is needed so your plugin will display correctly in our repository, but also so we can make sure you're providing the users with all the information they need before they install your plugin. Our goal with this is to make sure everyone knows what they're installing and what they need to do before they install it. No surprises :)

Could you send a link so the completed plugin can be downloaded please. Alternately you can reply to this and send a .zip or .rar file.

1) Upselling is fine :) But remember that you need to have all the transactions take place on your site. You can't use WP as a salesground or storefront, or your plugin will be removed.

2) Uploading new themes needs to be handled in a way that won't break when you upgrade. If you upload a theme to /wp-content/plugins/vimeography/themes/ then when someone upgrades vimeography, they'll lose all their themes.

3) Make sure you test all your themes with the default WP theme. Right now, the default vimeography theme looks horrible on TwentyEleven, due to the weight of the videos (which is really a Vimeo/video issue, but you need to account for it.)