The best chance for success will be with just rudder and elevator, leave the 4 channel stuff for the "gurus" who want the extra challenge and weight.
The difference in weight between spruce spars and balsa [for the overall weight of the model] is negligible compared with the added strength. Really tough, hard balsa might work OK, if you're a good judge of wood then have at it.
The real weight gain / savings comes from your choice of covering technique, hardware, and onboard equipment. The easy way is usually the heavy way. If this stuff was too easy, alot of us wouldn't do it, we'd just fly ARF .40 trainers
Landing gear for a model this size and weight will only hurt performance and make landings more of an adventure..