Well FiferMG4 hope your enjoying your car we are for sure.
So Zappi
1 There is no need for any cover at all it is fully weather proof I personally don’t need that anyway as mine is in the Garage anyhow but you don’t need one.
2 connecting solar to Zappi at a later that should not be any problem at all As the only connection is via a CT clamp from the meter tail to the Zappi as far as I know and your installer can do that at the time I’m sure.
3 now that’s a difficult one really as getting it installed before you get the car that I would do then you have it there ready,I would have a ring around or email a few installers to check on availability and then book it in to be done just before your car arrives, says week or two, I used the MyEnergi web site to find installers in my area but back then 2/3 years ago there weren’t that many around nowadays the are loads on the Internet to sound out plus if you book it in now you be able to fix a price.
Hope this helps
Les