I'd use the pine. The turpines may slow rotting a bit, but nothing dramatic.
It makes the garden smell all festive and christmassy too
Every 'edu' site I've looked at says the acid thing's a myth.
here's one
It always reminds me of the old "if you use wood mulch, it'll
suck all the nitrogen right out!"
I
would avoid putting wood mulch on areas they'll be dug, as I think high-carbon mulches dug into the soil can cause quite a bit of nitrogen-tie up
until the soil critters get it all back in balance.
I've never used drip irrigation so I can't speak for or against it, but for me, a big positive with soaker hoses is that they're basically just one big 'leak', so can't get blocked.
I've heard people have nightmares with blocked emitters and so on.
Not something I'm familiar with, but maybe worth considering in your climate: because water can't pool/expand in a soaker hose, apparently many people leave them out all winter in cold climates with no problems.