Regarding your first point about countering artillery by sending in single infantry to draw the fire, I think this tactic is much less effective now because:
1) Your artillery stack gets a morale boost from killing single infantry (usually 1-2%).
2) Your artillery stack can fire again after killing the 1 infantry (if you have sufficient artilleries in your stack).
What this means is that this single-infantry tactic is only effective when you have very few artilleries in your stack. When you have more artilleries and more infantry in your stack, this tactic is not effective and may even backfire.
In other words, I suggest you counter this tactic by (i) putting more artilleries in your stack (so it can fire multiple shots), and (ii) put a lot of infantry in the stack (so that you will benefit more from the morale gain from killing the infantry).
I am not against your suggestion of having different 'fire only' mode, but i will personally not use it even if it is available. This mode is too easy to counter. For example, if an enemy stack is using 'fire only on arty' mode, I will send my infantry to attack that stack, and then move my artillery to bombard.
For your 2nd point, I think the developers are already working on something to fix this, so I won't comment here..
