They do recommend breaker sizing, on the middle of the manual (Parallel inverter section).
The LV2424 has an overcharge function, where it goes from inverter to utility automatically in case you exceed the 2.4kwh. It happened with mine several times... i guess it could do some damage overtime but if you correctly sized your system it shouldn't happen very frequently.
As far as im aware you should size the fuses to protect your wiring. For example in my house i have AWG14 going to the 1st and 2nd floor, so i ended up using 15A fuses instead of 25A. (Well in reality i have 2 inverters in parallel, so i have a 50A fuse, and from there it goes to the secundary 15A breakers).