rear routing means the there is no need for a pick guard. les pauls prs styles most jackson charvel and ibanez style super strats are back routed. the pick ups cavity are step up so you can 'mount' the pick ups directly to the body or use pick up rings that look like square O rings almost (think les paul here) to mount the pickups. also the control cavity has a plate mounted over it on the back of the guitar so only the shafts of the pots/ switches show.

you should beable to get the termolo with a rear routed body. but you might want to also look into other desgins too like kahler bigsby and every other one out there.

a one peice body depends on how is was cut. verse three peisce bodies or two peice. if you put the body together wrong you can dis rupt how the sound travels through the body, but a once peice thats cut wrong can do that too.

have you found the exact pickup set/ indivudal picks you want yet? have you looked into gibson ducan dimarzio emg fralin carvin and every other type on the market?