quartus 9.1 and nios 7.2

if you upgrade from 7.2 to 9.1 to recompile your fpga i would open the sopc builder (9.1) regenerate the sopc project and then recompile with quartus 9.1 so your project is uptodate

but regarding your questions about ide 9.1 maybe somebody who works with this ide should answer, sorry i can't help you with that. try to open the ide, and as far as i see mostly it is selfexplaining how to import an existing project and to upgrade it from an older version. try and error :-) but don't forget to backup ... you never know :-)