Okay, lot of questions here... Let's get cracked <breaks finger while cracking>. Damn, been a bit…
Personally, I like the subtle hints peppered throughout. When they all come back around at the end and you can look back and go, wait a second!" When reading, that's part of the fun. As for too subtle, I think everyone has a different interpretation of subtle and how much or little is required.
While I'm sure I'll have tomatoes thrown, there are some people who don't read for the hints. Personally speaking, I don't always. (Put down the pitchforks!) I know people who read mysteries just because they like the author... And others will actively try to solve it before the character does... (One where I used to work would be reading a James Patterson with a notebook next to her, taking notes...)
On a personal level, again, I can only say that I prefer not knowing a clue and solving or being surprised at the end... Like you, that's part of the fun. Hints are good (although I probably wouldn't have figured things out on The Divine Hand without a little prodding... Hopefully that comes around a little more...)
All that incoherent rambling aside, best advice I can give, write what you want to read. If you like having hints strewn throughout, go for it. If you do, someone else will too.