I don't see a firmware for the T54W nor is the EXP50 available.
These phones are basically new since October or so. They will not be in EPM anytime soon because of how that has traditionally worked. The device manufacturer has to sing an agreement with Sangoma (Schmoozecom) to get a device supported. I assume, but do not know for a fact, that the agrement includes monetary compensation also, as anything in EPM is fully tested by Sangoma also, and testing takes manpower (money).
I am interested in Zulu but never set it up because a 2 users license for only a year is useless. Or does that auto renew so I always have 2 users for free? If that is the case I will set it up on my company PBX for myself and another user.
None of my clients have had an interest sadly.
Same here, time out free licenses I generally avoid.
At this point you can go through the new system one piece at a time and make sure you are good.
Change a couple extensions to point to your new PBX and make sure they register and can call each other.
Once you are sure that the basics are working, disable the trunks on the old system, enable on the new system, and verify outside connectivity works.
Finally, you can change the rest of the extensions.
No, you are missing the entire point. There is a reason that Elastix dropped FreePBX in 3.0. There is a reason the the PBXiaF team has spent the time and effort to come up with the Asterisk GUI distribution.
Both teams obviously hope that nothing changes as they are also continuing efforts with their products that use FreePBX.
FreePBX is a horrible interface. It is dated and sad. It works, mostly, but leaves a lot to be desired. Ever since FreePBX switched from being an interface to being a full on competitor to Elastix and PIAF they have had a huge incentive, really a need, to develop their own thing. If anything, my guess is that they hope that FreePBX does do something drastic and force them to either take over or abandon FreePBX, not that they fear that. I felt for years that they needed to do this, having nothing to do with source worries with FreePBX.
Simple business pressures would make them do what they are doing. Nothing more is needed.