Content Type Hub questions

I have a couple questions in regard to content types published from a hub

Right now we are in very early stages of setting up our sharepoint farm. We have a Content Type Hub, and our main Information Services site collection is our main consumer of the content types. The Hub has 3 document content types used for help desk documentation. In the Content Type I have 2 customized columns that are used in all three document templates.

1. If I have/want to delete one (or all) of the existing content types 6 months from now, can I? I ask because I was playing around today and attempted to delete one (I messed it up when setting it up) and I kept getting an error saying that the content type was in use. I literally had to delete EVERY document that was saved using that content type, had to clean out the recycle bins, etc, before I was able to delete the content type. Is that normal? Do you all ever delete content types months down the road fi you don't use them anymore? or is it just best to reconfigure/repurpose them?

2. The custom columns that are in use are created on the Hub, used in the Content Types on the Hub. If I modify the columns at all, how do I make sure all the downstream site collections get that update correctly? Do I have to republish all the content types that use that column before the consuming site collections will get the updates? There has to be a better way of doing this.

Thanks in advance

Jason