Hosting images externally never had any impact on cases I had a chance to observe. The only problem I can think of is that you lose control over loading times or if somebody takes an image and links (credits) the image hosting domain instead of your domain.

Agreed, community is something that can not only educate but get you going and inspire to do more and better. It does get a bit lonely if you are hiding under a rock for too long.

There are several types of penalties (single keyword, all keywords, complete ban...etc). Search for your own brand and if you don't come up with anything than you're likely banned. Same thing with domain, site: command and info:

Likely it's not banned then - just not worth indexing. Chuck some decent content up there and you'll be fine

If your network is not a secret then ensure that you have full and clear disclosure on the site(s). I remember Matt Cutts once said this as an answer to a similar question on YouTube. Private registrations are common for non-SEO purposes so Google cannot act on it alone. However if you have 1000 domains with private whois that may start looking a bit suspicious.

Copy the site, set it up on a staging server and run http://www.xml-sitemaps.com/ on it?