After the upgrade process finished I observed that not all mibs files were updated. Then updated to MIB kit version 10.
Anyway, overwritten settings related SNMP traps is not a big problem, because I can ( in fact I already did it ) disable the ones that I want, just as I did before in version 7.3.
The big problem is at point 2.
Predefined, user defined collections for systems and events are not filtered correctly, e.g: predefined "Major Systems", "Critical systems",... or my ITAC defined collection, all show me all the systems, or "Old Noisy Events", "Important Events"... or my "Events newer than 30 days" defined collection, all show me all the events.