best thing is to get a good bicycle repair book and start Reading it..
the Park Tool "Big Blue Book" is the most common one, but may take for granted that you are already a mechanic.
here's a great source of info on such books...
https://www.powells.com/books/search...r+books&page=1
a good book will teach you about the nuances of bike design and specifications, and spare you from endless anecdotes,
start by determining the SIZE and TYPE of steering stem your trek needs.. then,, Brake Caliper Reach and Style.
trek 1000 frames use 700C wheels, btw......
and a tool you may want quickly is a digital caliper for accurate Metric Measurements