VEVOR 2 Rolls of 1/2" x 100ft, Non-Oxygen Barrier Flexible Pipe Tubing, Red&Blue for Hydronic Radiant Heat Floor EVOH, Water Plumbing Applications with Cutter

It is 100' each.

No, it isn't sunlight resistant. It must be protected with a casing for outdoor use.

Yes, this is feasible. As long as there are matching pipe fittings.