1, How do we reconfigure the adobe launch and analytics to include this new domain?
2, During the parallel run, if we had some existing adobe launch tags built under the old domain, they would still work fine to collect conversion/traffic data as long as there is redirection to the new domain?
3, If we introduce a new subdomain (e.g. subdomain.abc.com), how do we add into this domain list in adobe launch?
In Adobe Launch, I added the new domain to the property's settings. This is optional, actually, because Launch doesn't really make use of the domains listed in the settings for anything.
In Adobe Launch, I had some data elements and rules that were "hard-coded" with the old domain. So I updated those to the new domain, or in some cases, re-worked them to be domain-agnostic.
In Adobe Launch, I updated the ECID extension to use the new tracking server provided by Adobe (after the first-party update for ECID had completed (see the first bullet point above)).
In Adobe Launch, I updated the Analytics extension to use the new tracking server provided by Adobe (after the first-party update for ECID had completed (see the first bullet point above)).
In Adobe Launch, I updated the Analytics extension to include the new domain under the "Never Track" section.
In Adobe Analytics, I updated the report suite's Internal URL Filters setting to include the new domain.
I think those were the changes that I needed to make minimally for the domain migration. There were a few other changes that I needed to make, but I think those were specifically for my client use-case, and don't apply to all clients. You should definitely check your entire setup (ECID, Launch, Analytics) to see if there are any situations where the domain name is "hard-coded" or fixed, and update those appropriately.