"Rev Matching"
 

When I downshift, I leave the clutch in and rev it up to about 3000-3500 then let the clutch out slowly, which makes it very smooth. Also, in my upshift with the clutch still in, I tap the gas, then let it out to make it smoother as well. Do either of my habits wear the clutch out faster or perhaps are harmful to the engine? Thanks for any input :)

It's clutch friendly. If you do it correctly, there's no harm done.