Although my G scale layout is currently in boxes, I also recommend avoiding plastic track.
I've bought all my track from here:
http://www.thefavoritespot.com...chmann+g+scale+track
They also have an Ebay presence and are located in Texas i think.
Ebay is a good place to shop for G scale items, I always do the "But It Now" and look for the cheapest price.
Here's a list of Part Numbers of Bachmann 4-6-0 engines that have the metal gears (I got this list from another forum):
91601 EBT 10 2011 ~ Loco 4-6-0 Annie East Broad Top Ver 6 Metal Gears
91602 D&RGW 178 2011 ~ Loco 4-6-0 Annie Denver & Rio Grande Western Ver 6 Metal Gears
91603 RGS 25 2011 ~ Loco 4-6-0 Annie Rio Grande Southern Ver 6 Metal Gears
91604 SPC 22 2011 ~ Loco 4-6-0 Annie South Pacific Coast Ver 6 Metal Gears
91605 D&RG 10 2011 ~ Loco 4-6-0 Annie Denver & Rio Grande Ver 6 Ver 6 Metal Gears
91606 ET&WNC 11 2011 ~ Loco 4-6-0 Annie Denver & Rio Grande Western Ver 6 Metal Gears
91607 none none 2011 ~ Loco 4-6-0 Annie painted unlettered Black Ver 6 Metal Gears
Bachmann also sells a lot of the parts online.
Do we have a list of G scale vendors on the forum? I have a good listing in my "Favorites", but I always seem to go back to My Favorite Spot when I buy.
If I was going to do outdoors I'd go battery-operated, remote control (none to little wiring to worry about). Blue Rail trains I think is coming out with a bluetooth circuit board for G scale that will be controlled from your Ipad/phone, etc (not sure what that would be like with the sun reflecting off it).