Review numeric fields in models, make sure to choose a proper size and to be consistent

[sameh-farouk]

Description

The same field in a model would be uint and in another model int or int64 and there is some conversion here and there. we should agree on specific types and use them always.

another thing, I understand that int64 is/should be big enough, but is there any reason to use it vs unsigned type for things like time interval, resources, and entity ids?