Moving an existing website to a new domain

We are in the process of creating a strong brand identity for our products. One of the issues in our brand building is our website URL. We have our website on our Company's name and all our brand urls are 301 redirect to our company name domain. If we change the domain URL, it will affect the traffic due to SEO impact. The following are some of the major factors

• The back links
• The Page Rank of the domain
• Web pages position for various keywords
• Age advantage of the domain

As it is a critical operation, we wanted to implement it in steps. Otherwise we will loose the traffic immediately.

• First, put up a small selection of urls on the new domain and establish a single Webmaster Tools account that authenticates us as the responsible party for BOTH domains.
• Next, we have to plan for our 301 redirects. We should not 301 the entire old domain to the home page of the new domain. But also, should not use a separate 301 for thousands of urls to thousands of other urls. Use a 301 for the most critical relocated urls. The rest of "lower importance" the URLs can serve a custom "we have moved" message with a true 404 http status code.
• One other step - work with the backlinks. We have to contact major backlink owners and request a change .
• Start establishing NEW backlinks as soon as possible, so let a lot of people know about the new site, in a way that encourages new links.