Truss Plate Loose where rafters meet

If the purpose of the plans is to just protect against damage, I think your plan is probably fine (you might not even have to cut them down to size, I don't see the problem with it overhanging a little bit).

However, it's not clear to me based on that document exactly what the purpose of the splice plates are. To me it sounds like the splice plates are on the outside faces of the braces, nailed through from both sides.

I would call the truss manufacturer to find out specifically what their bracing requirements are.

The split top cord should be repaired. Lay a 6 or 8 ft long 2x4 or 2x6 across 3 or 4 of the bottom cords, then use a length of 2x4 to push up to close the split. When it is aligned properly, nail it in place with numerous nails that are the type that do not causing splitting. Then sister on 3 or 4 ft (or more) of 2x4 on one side of the repaired section. If protruding roofing nails prevent sistering on either side, then you might have to use a 2x3 on the side and on the bottom edge.

(You might squirt wood glue into the crack before pressing the crack closed.)