Rack Advice

Yes it's me again fellow audiophiles and enthusiasts.

Rather than buying and rack stand for my growing audio collection my brother (a professional cabinet maker) has offered to build me one of my own design as my birthday gift. Obviously I know that minimal sides, back, etc are desirable to prevent resonances but I still have some questions concerning materials....

1. What type of wood? Maple, poplar, mahogany, paduc(sp) or some other?
2. Should the rack have spikes for feet?
3. Should the rack be standing on something other than my hard wood floor?
4. Any other advice you may have to offer.

Thanks!

Erik