I laid my garden railroad with some handmaid track, but I quickly decided to build my own switches and buy plain track, as hand spiking is very boring. I used rail and separate tie strips on the plain track.
Redwood and cedar are best outdoors, as most wood will rot due to contact with moisture. You could use pine and liberally apply wood preservative every year.
Scale spikes are/were readily available from Micro-Engineering. Don't use stainless, as the lack of rust means they will work themselves out. Regular steel rusts into the wood of the ties, and the rust on the head protects the steel, so they work well.
Pre-drilling the tie for the spike makes it much easier to insert them, especially in redwood which has hard rings. I used a small Dremel cordless drill.
There were spiking tools for smaller scales, but I never found a satisfactory one for g-1.
I used code 250 aluminum, which is much more scale size, but subject to damage from human or animal feet. I sprayed the rail rusty brown primer before using it.