fascia facsia

Can anyone name the white channel piece above the 2x4 rotted wood I’m trying to replace. Any suggestions on materials needed to replace?

There are several spots where it appears the fascia board has sagged and/or rotted and the roof has lifted. It looks like the roof overhangs the fascia by about a 1/2 inch. Can I just take off the eaves, the metal between the eave and the fascia and then put in a new fascia board? It looks like...