I recommand using a hybrid build with firestaff and waterstaff. Waterstuff pushes enemies back and stuns them so you can go further away. Taping the firestaff once kinda stuns them. You can then spam them with the waterstaff to death while always walking a few steps back before shooting to kill them without them reaching you.(You can use the shield to get some room to breath)
The watercircleskill is great for crowds and does absolutely terrible damage with low wisdom. It did like 20 with 30-40 wisdom. Dont ask me I am no expert but I have now 70 and it does with both proccs if they are close 100. It is my go to spell to kill actually everything. Nothing can evade that.
Stamina has nothing to do with being depressed I think and even if the tradeof is worth it. Always keep humanmeat or brains in your inventory eating one of these gives crippling depression.
The con wont make a big difference. It's better to kill them faster that will save more stamina. Pump it all into wisdom after getting 10 in stealth. The damage increase feels exponential with some spells.