Without knowing much about what the request is, I don't believe there is a way for the report to run from the bottom up, but you could possibly do a couple things to fake the system out.
For example you can do something like in the following link to put your summaries in the header:
http://stackoverflow.com/questions/1662322/crystal-reports-global-variable-running-total-not-displaying-in-header
Then you can play with the sorting of the details if you need the rows to go in decending order.
Hope this helps.
[EDIT] I see you updated your question so I'll add an update to my answer.
One more thing you can try out is to play around with the Print at the Bottom of the Page and Keep Together properties of the sections. I haven't tried this, but one thing you may be able to do is put the section at the bottom of the page and perhaps find a way to have the section grow from there. You will have an issue if the page goes to another page and though it seems possible in my head that the section could grow while being placed at the bottom of the page I haven't tried it so it might not work. I am just throwing it out there for one more thing you can try. Hope this helps.