Mike,
I have listened to a Cambridge Audio 640 (amplifier/cd player) combo with a pair of Arro in a local Totem dealer. The bass is tight and clean. The midrange is quite revealing. Pretty good for a system that cost less than $2.5K (Arro speakers included)
# 1, I recommend to go with a quality solid state CDP first. Then save money for a decent sub like REL or TOTEM STORM.
# 2, Naim CD player is recommended to me by Vince at TOTEM and I just pass on the courtesy.
# 3, I think you want more bass, so see my answer on your # 2.
# 4, only you know the answer.
# 5, You have a tube amp which is already warm. Why need another tube CDP? The bass produced will not be that good as a good solid state CDP like the Naim/Rega.
# 6, I suggest Denon if you want a Japanese brand. Otherwise, my choice would be NAD, Rega, and NAIM (low fi budget, mid fi budget, and hi fi budget in that order)
The sub should be your last issue. I am a TOTEM/NAD guy myself and I own a pair of REL and a pair of TOTEM STORM.
Hope that helps.