Extending Capabilities of Modifier

There may be other ways of doing this but have not figured them out. I think that modifier features could be easily extended.

  1. Modifier that shorten/lengthen something, I frequently want to cut some things down to size or make an extension of model shorter, have to sometimes slice several times, mesh Boolean etc. Would be nice if could just put a modifier on it and stretch it out to the length I need or shorten it.
  2. Kind of related to above often need to take a part and slice for example an inch in the model between top and bottom, a modifier that would do this would be great. Tried with cut but involved multiple cuts, lining up pieces, using mesh boolean to union the pieces and a lot of eyeballing trying to get lined up just right.
    Just a thought might be a way to do with cut feature maybe.