preserving hot peppers without damaging heat
The heat in peppers (capsaicin) is quite stable.  Any number of preservation options will work, as long as you include the hottest part of the peppers which are the ribs and membranes holding the seeds.

You can choose a method based on your goals and ambition:


Pressure canning
Dry them (follow guidelines from a reputable organization, for example links below)
Freezing
Pickling (and canning)


For your use case (storage for a few months prior to making hot sauce), freezing may be your best option.

See also:  


UC Davis guide to preserving peppers
Penn State Guide