As far as I know, there is no damage bonus from bowcraft/fletching.
Anatomy gives a much lesser damage bonus than tactics. So if you need to skimp on one, skimp on anatomy. Even with healing (the primary reason for anatomy) you are fine with only 61 anatomy unless you wish to res others. (61 is the magic number for cures.)
Damage bonuses from skills apply over and above the item DI cap of 100% and even over the total DI cap of 300%, so you will lose a bit of damage from not having 120 tactics/120 anatomy. But it is not that big a deal.
From a random FoF:
Damage Increase and You
"For PVP and PVM: If I have gm tactics, gm anatomy, and 125 str how much DI percentage do I have w/o items?"
Stratics has the correct results for these calculations.
+68.75% for GM Tactics
+55% for GM Anatomy
+42.5% for 125 Strength
"People are saying there is a 300% DI cap for PVM, is this true? "
Yes, this is true, Damage Increase is capped at 300% (or a 300 internal damage rating). However, anatomy, tactics, strength, and lumberjacking are NOT included in that cap.
"If I have 300% DI and I cast Enemy of One will I even do more damage?"
If you already 300% Damage Increase from special moves and profession abilities, then the answer is no, Enemy of One will not increase your damage further.
Note: that a slayer weapon is double damage (a 200 damage rating). Enemy of One has a rating of 100. The combination of those two alone would reach our cap of 300.
"Are slayer weapons included in the PVM cap for DI?"
Yes.