1) For preference I would use the Bticino ones, around the same price as Schneider. These are the units guaranteed to fit and will maintain any type-approvals.
Nano and Chang are both low-cost alternatives, I've not used their plug-in units but the DIN ones are fine.
Schneider / Square-D are, of course, a well-known, decent quality brand.
2) Do you have your permanent supply meter? If not don't replace your incomer until the inspector has been and gone.
What size meter do you have? I wouldn't go over 65A on a 15/45, it's not going to explode but the accuracy falls off at high current, bet it won't read low!
Is your incoming cable copper or aluminium? 16mm2 copper should be good for 90A in free air, aluminium 70A.
As always, Up2U.