I'm trying to understand how Zoho works with multiple domains and aliases but it is very complicated and poorly explained in so far as to what's actually possible and how much it will cost.

I have gone though these forums finding questions from others with the same misunderstandings and difficulties but somehow, even though I now have a rough understanding, I am still left with more questions than answers.

To explain my situation:

1) I send and receive only a few emails per day across a few domains that I own (and a couple of free gmail accounts) and mostly I am the only user - from any of those domains I may have several identities (e.g. me@, support@, sales@, etc.). Some of the domains have a catchall so that I receive everything to those domains.

2) Two of the domains have me as the main catchall user, but there are a couple of extra email users who have their own mailboxes (e.g. my kids on a family domain).

3) I currently handle all my email using Thunderbird email client to collect from all the individual email accounts and I can easily see, differentiate and reply to all emails in one easy "Unified" Thunderbird view.

4) I want to move my email accounts to not be hosted alongside websites (all currently on a cPanel server) and I think using a solution such as Zoho to host my email seems a good plan. I cannot afford a cost per email address/user/domain every time I set up a new test domain, email address or user, so I'm hoping to run my small amount of email traffic through (ideally) just one Zoho account which I believe I can do using Aliases and Multiple domains.

5) However, from what I understand so far with Zoho, there is going to be a problem with having Aliases and several users at the same time (as per point 2) - is this so and therefore I will need an extra paid subscription for each domain that is not just me accessing the emails?

6) If 5) is true, and I do need several paid subscriptions for when there  is more than one user, can I still "unify" my catchall of email (for those domains) for the other Zoho paid accounts into my main Zoho Aliased domains account?

7) Lastly, whatever shows in the unified (all domains emails) Zoho web-app view of all Aliased domains, will I still be able to continue using my Thunderbird email client in the same way as I do now and easy differentiate, read, send by each userXXX@domainXXX.com at will, or will the aliased Zoho domains somehow be amalgamated in a way that becomes unclear in Thunderbird?

 
I'm hoping that all makes sense, it's a complicated thing to explain. My main concern is the blur/cross-over between Zoho aliased domains, the number of users allowed (which I think is 1 on an aliased domain), what happens when one of my aliased domains suddenly requires two or more users, and how it all functions/works/appears in Thunderbird (or any email client).

Is any of what I require possible and what's the most logical/cheapest way of accomplishing it?