[cypher]

I wouldn't worry about the hoarding, some hams hoard more than others, seed mix doesn't go off although it will get a bit stale after a while, it's fine to leave them alone but if you do think some needs clearing out after a while or you need to clean an area of the cage where some food is hoarded you can just clean it out & put a little fresh mix back where it was.
I wouldn't clean much after only 2 weeks as he'll still be settling in, if you can find where he pees spot clean there but don't do a full cage clean, maybe a partial cage clean after about a month but leave his nest a lone as much as possible.
What foods have you been giving him? If he doesn't like the new one & the old one has a good nutritional balance maybe stick with that, did you change mixes gradually? It's best to do the change over a week or so just gradually introducing the new food a little at a time.