Cyclocross - Cyclocross Build - Newb advice

Ok, longish time BF guy here, but I'm a road/tri guy. I realize there is a search function, but I'm looking for some specified advice, so save it.

I have a 7800 DA 10sp and a compact crank lying around on a winter/bad weather bike. I'm planning on building this into a CX bike. First question, 10sp work alright?

Second, I'm looking for a CX aluminum frame, but I'm not sure which direction to go. Looking at CAAD9, Spooky, Ridley, Salsa, etc. Please weigh in, is there a good place to find used framesets?

Third - I ride a 54cm road bike, do I stay consistent with that or do people usually size down for CX?

Fourth, I'm fond of Aliante saddle, does this work well for CX?

Fifth and final - any changes I should be aware of in my geometry? Lower saddle height? Bar width (42 road)? Stem (110 road)? Planning on 3T ergosum (same as road) Thoughts? I can use road wheelset with CX tires right?

Appreciate the advice, sorry I'm too lazy to search all of this out.

yes, ebay, same size, sit on it, higher bars, sure, duh.

i'm too lazy to write it all out.

size depends - some CX frames have higher BB to ground clearance, plus the tires add 5-10mm to bike height over 22 mm tires, such that standover can be a bit of a problem if you stay with same frame size. Many will recommend going a size down or paying more attention to top tub dimension.

I just built up an old steel Bianchi. Put Michelin Mud 2 tires on it.

you may want to size down. I ride 58 road but i like my cyclocross 56

I design our CX bikes (That's my job here at Spooky) to be shorter in the cockpit than a road bike by a good 3-4cm's, optimally with wide bars and 100 or 110mm stems.

I ride one of our 54cm road frames with a 135 syntace stem and 38mm bars, and one of our 535 cross bikes (with an Aliante) with a 100mm-17 stem slammed and 46cm bars.

If you go with the CAAD9 CX9 you may want to go down a size. I ride a 56 square road bike and I rode both the 56 and 54 CX9's and went with the 54. It is very comfy and stable.

1. 10spd good, 9spd better
2. All great frames. CAAD9 without BB30 doesn't seem right. I see a lot of Salsa's and Ridleys so my vote is for the Spooky with an Edge or Alpha-q fork.
3. Size down a pinch on your top tube. Aero-ness is useless in CX so you do not need to be stretched out. You also get better handling with a shorter reach. Don't go bananas though, just a CM or two with the TT.
4. That saddle is fine.
5. Bar width wider, flip your stem up, 3T is great if its the Pro (alu) then better, you can use road wheels with CX tires.

What wheels do you have?