weapons & inscribing

Can I put inscriptions + wrapping on weapons I have crafted/collected?

If they're inscribable, yes. If not, no. Check to see if it says 'Inscription: xxx' somewhere on the item.

And you can add a wrapping on any staff i do beleive. And you can only add an inscription like marty said if it has "inscription: None or Seize the day or w/e it is"

Generally speaking, weapons crafted/collected in Prophecies or Factions do not have an inscription slot, so you can't add an inscription. They do, of course, have an "inherent" mod that does the same as an inscription, but can't be changed.
Almost alll crafted/collected weapons can take a prefix (staff head) or suffix (wrapping) mod. Note though, that in some cases you can't remove a mod from some crafted/collected weapon, even one you've added yourself, (usually) if it already has a prefix/suffix mod such as "of charrslaying" fo example.