I'm not sure how well your mashing method will work. The liquid is where most of the enzymes are (which is why decoctions are usually pulled thick), this may cause problems converting the starches to sugars when you eventually get up to the saccharification range. For a sour beer it isn’t a big deal if you don’t get complete conversion, but you do need some conversion. Is your wheat flaked or completely raw? Rice hulls aren’t a bad idea, you can wait until the end to add them (.25 lbs should be enough).
I had a sample of Friek at SAVOR a few days ago, didn’t get much sourness/funk (but it certainly wouldn’t hurt). I would aerate the wort as well, you want a healthy/quick start to fermentation (my first Lambic took 4 days to start fermenting and had some off-flavors from primary fermentation). For most sour beers I pitch some healthy/known Sacch in addition to blends and dregs. Some yeast nutrient wouldn’t be a bad idea, but probably isn’t necessary.
Usually Lambics are boiled longer to get rid of any funky aromatics from the aged hops, may not be necessary if your hops smell fine.
Oak and Lambic are a classic pairing, but more for the microbial properties and oxygen permeability than anything else. You could certainly add ~.5-1 oz of boiled oak cubes either at the start or well into fermentation.
I would get rid of the hops since the beer will be sitting in primary for so long. That said I’ve visited a brewery that has a dry hop sock stuck in one of their barrels from a few batches ago and they haven’t had a problem.
Hope that helps, good luck!