There is a ton of different designs in snow/ice guards. What it does is it help to keep a person from getting killed having an ice sheet sliding off a roof, It also helps stop the gutter from being ripped off the fascia.
We have a of very old standing seam roofs and slate roofs here. And they are a standard in roofing. Spacing varies. We usually put them every 24" along the roof. Need to stagger them form 24" of the lower edge and 48" from lower edge. This helps break up the sheet of ice/snow.
Snow Guards for Metal Roofing
Snow Guard Spacing and Layout Tool
https://snoblox-snojax.com/?gclid=CO...FRSfnAod2leKnQ
You can our are probably going to use a 2x8 for a fascia board for scale and also it being a 2x8 as opposed to a 1x8 because of the 4' spacing on the truss. Or use a 2x6 and bring that starter perlin on top to top of fascia board.to get the width. Temp lay out a perlin at the end of the fascia. Measure down from there the width of the fascia board this will determine if you need to cut the bottoms of the tail piece which doesn't usually happen. Keep that distance 12" away from the building you will get full usage from the vented soffit material no waste. Don't forget to take into account the perlin width thats around the top edge of the plate. If you already have 12 inches from that perlin/plate then the choice here is to cut the end of the tail piece to shrink it down or keep the wider soffit.
I use alum for soffits. Doesn't vibrate in the wind like vinyl. To cut that lay out saw horses and a plank. Lay alum soffit on the board with a couple of block scabs to raise the soffit or lay the soffit material on the sacrificial plank.
Tape the bottom shoe of the circular saw and put a plywood blade in the saw back wards to cut soffit material. You can use a pair of snips but I lay out the soffit in 2 or 3 pieces and gang cut them. You will need a wide thick screwdriver to re open clean the slot grove and a utility knife helps. so that slot is totally open to slip into one another. Measure the soffit length to adjust for the first cut if need be so you don't end up with a sliver at the other end.
I box the end of soffits to the end wall to gable wall. Oh make sure you lay this all out in heights if you are buying the pre bent fascia material to meet its widths.
Not sure what width rake metal "drip edge" you are getting be aware you loose some width with the standing/ribbed seam and the soffit metal thickness.
Are you getting the rain shield for the door roller track? If not do