two semi-independent domains (should I worry?)

[gadgetman]

My company is in a strange situation because (without my knowledge) there have been recent changes, and I'm wondering about possible SEO-outcomes and fixes. Here are the facts:

    Imagine that our original domain-name was eastgadgets.com and our website had pages with URLs of www.eastgadgets.com/east/east1.htm and www.eastgadgets.com/east/east1.htm, etc, and everything was on an east-coast server.
    We then developed a new website on a new west-coast server, with a domain-name of westgadgets.com and pages www.westgadgets.com/west/west1.htm, www.westgadgets.com/west/west2.htm, etc.
    Over the years, external websites made lots of links to the old homepage, www.eastgadgets.com but not to www.westgadgets.com
Now the homepage has been moved to the new server and its new URL is www.westgadgets.com
     There has been a 301-redirect (maybe on the old server where the old-URL homepage used to be, or maybe on both servers?) from www.eastgadgets.com to www.westgadgets.com
     But pages on the old server (www.eastgadgets.com/east/east1.htm,...) continue to have the same URL shown in browsers, because somehow (the webmaster hasn't explained how it's being done) these pages are not being 301-redirected to a URL containing westgadgets. This semi-direction, with the homepage being redirected but not interior pages inside the east-directory, is what I mean by a "semi-independence" of the domain-names.
     Using www.internetofficer.com/seo-tool/redirect-check/ there is a "direct link" when checking for www.eastgadgets.com/east/east1.htm / And for a check of the old homepage-URL, www.eastgadgets.com, it says "Type of redirect: 301 Moved Permanently     Redirected to: www.westgadgets.com".

    Here is what I think will happen: All link-credit to the old homepage will now go to west-pages (westgadgets.com/west1.htm, etc) and none of it to east-pages. Is this correct?
    And I think a decline in SE-ranking for the east pages will happen suddenly, with a quick drop from a high level (with links-credit from the homepage) to a lower level (without the links-credit). Is this correct?
    If the answers are yes and yes, how long will it take for the sharp drop to occur? How long will the east-pages retain their former SERP-rankings, before their quick drop to a lower level?

    And a question about a possible solution:
    There are now two servers, so is it technically possible to use the same domain-name on both? Specifically, could interior-pages on the old server (www.eastgadgets.com/east/east1.htm ...) and a homepage on the new server (www.eastgadgets.com) both have eastgadgets.com in their URL?
    If yes, I think a 301-redirect of www.westgadgets.com to www.eastgadgets.com would lead to all pages (on both servers, east and west) having browser-URLs with eastgadgets.com, and an equal spreading of homepage links-credit to pages on both servers, to both east1.htm/etc on the old server, and west1.htm/etc on the new server. Is this correct?

Hoping for help, to reduce my concerns and confusion,
Gadgetman

[phranque]

All link-credit to the old homepage will now go to west-pages (westgadgets.com/west1.htm, etc) and none of it to east-pages. Is this correct?

a 301 response will pass the "link credit" to the new location.

And I think a decline in SE-ranking for the east pages will happen suddenly, with a quick drop from a high level (with links-credit from the homepage) to a lower level (without the links-credit). Is this correct?

whether this will happen and if so how quickly will depend on a lot of factors.

There are now two servers, so is it technically possible to use the same domain-name on both?

yes it is technically possible.
easily with different subdomains.
if you want to use the same hostname and host the subdirectories on different servers i believe you will need to use something like mod_proxy [httpd.apache.org].
why do you want to spread the links-credit to both servers?
i would figure out what you want the url for each page to be and then figure out the technical implementation of that rather than backing into a solution.

[gadgetman]

Thanks, phranque, for the useful information, re: mod proxy, etc.

>whether this [SE-status decrease] will happen... will depend on a lot of factors

Only the homepage, www.eastgadgets.com/index.htm, is being 301-redirected to www.westgadgets.com/index.htm. The interior pages on the east-server (inside the directory "east/") are not being redirected, so they still retain eastgadgets.com in the URL shown in a browser window.
    If both types of pages, east & west (www.eastgadgets.com/east/east1.htm, etc, and www.westgadgets.com/west/west1.htm, etc) have equal numbers of links from the homepage, equally located on the homepage, will both pages (east1.htm and west1.htm) get equal SE-credit from the many external links coming into the homepage?
    Or will the fact that homepage and west.htm share the same domain-name in their URL, and are both on the same west-coast server (by contrast with the differing eastgadgets.com URL and east-coast server for east.htm) give more credit to west.htm than to east.htm?

gadgetman

[gadgetman]

     My first post in this thread describes a complex situation, probably one of a kind, with technical issues, so I wasn't expecting lots of replies, and I appreciate phranque's response. But my second post is about the basic logic of SEO, re: the importance of LINKS and DOMAIN-NAME. I'm sure lots of you know the answer, and I (and maybe others) would also like to know it.
     In the final two paragraphs of my previous post - "If both types of pages, east & west..." - imagine that everything is equal for east & west websites, except one has the same domain-name as the homepage and the other is being 301-redirected.
     Will pages in east & west websites have the same SE-ranking (this will occur if only links matter) or will west1.htm rank higher (this occurs if having the same domain-name as the high-status homepage is also a factor, in addition to links) ?