1. Redirects should be done via CNAME or not at all. It's very possible for web page redirects and iframes to hurt your pagerank.
2. Set up Google Webmaster Tools for all domains, tell Google which one the main one is.
3. If the title and URL match for keywords, you get bonus points.
4. Content above the fold matters more, even to spiders.
5. Make the site active. The more updates it has, the more times google will index it, the more times it'll index keywords.
And most importantly: Links and link placement. Post links on social media. Any sale/deal/announcement for this company should be plastered across all social networks. Get active in the social internet for your company's sector: comment on other content, link back to your site.
Also, linking from your site to other sites can not only hurt your page's pagerank (if it's to a misbehaving site), but also lower your pagerank vote power (the more watered a site with links, the less each site's link's value is).
Besides that, making sure your site is easily indexable goes a long way. If you can figure a way for a blog, that can help too.
Bottom line is that it's very difficult these days to get high up in the ranking without decent amount of effort at promoting so other sites are linking to your site, or luck at suddenly finding yourself in the center of some popular internet trend/craze.
Well, this really depends on what keywords you're trying to get on page #1 for. If keywords are in your title, in your URL, and your site is updated more regularly than other sites with those keywords, you'll easily go up high.
Thanks to having a fairly uncommon last name, with a bit of site updates, my family domain was able to get a high ranking for family member name searches. If I were to put my name in the title of my blog, I have no doubt I'd jump up to into the top five for a google search of my name (currently at the bottom of the first page).
Choosing what keywords you want to be optimized for is probably as important as any other aspect.