In NE Kansas (the interface between US climate zones 4 & 5) with 2x6 w/cellulose cavity fill you need a minimum of R7.5 foam on the exterior, and while that would put your center-cavity R at about R28, even with a 15% framing fraction (advanced framing technique throughout) you'd be at about R22-R23 for "whole-wall" R. For typical 2x6 24" o.c. framing fractions you'd be at about R21-R22.
To get there with a low-E reflective layer you can use foil-faced polyisoi @ 1.5", but I'd strongly recommend going with 2" instead (two layers of 1" with seams air-sealed with FSK tape on both layers) which would get you some dew-point margin on the wintertime moisture loading of the sheathing, and would get you closer to R25. The cooling season performance improvement from the foil is small but measurable, the heating season improvment is nearly nil (more theoretical than actually measurable). Window & roof gains are far more significant for controlling cooling loads.
Also, using ICF for the foundation,and placing the foundation sills such that the insulating sheathing of the upper floors is co-planar or slightly proud of the exterior EPS of the ICF works well. Even an R16 (2" EPS both sides) ICF is appropriate for your other R-values, so feel free to cheap-out there, and you wont' have to cantilever the foundation sill off the concrete to get the foam-planes to match. ICF is nearly idiot-proof when going only 8-10', so it's very low risk compared to doing the whole house in ICF.
Thermal bridging at bumpouts is pretty high, so having the 2" of exterior foam is a real plus there.
Similarly, if there are cathedralized ceilings for some or all of the upper floor, using ~R20 foam above the roof deck (4" of iso) and 2x10 rafters with R30-35 cellulose cavity fill works. The 4" of foam thermally breaks the rafter, and at ~R55 center cavity it mitigates the risk of ice dams even without a vented roof deck. It also puts all attic ductwork (if any) inside the thermal and pressure boundary of the house, which limits the conducted & leakage losses to the exterior, and limits the amount of air-handler driven infiltration that the AC would have to dry out in the summer. Exterior foam on roof decks is standard stuff in commercial building, but if your contractors balk you can use pre-laminated nailbase polyiso (Hunter-Panels, Atlas, and other iso manufacturers have several variations on the theme) which have straight-ahead prescribed mounting methods- no engineering required. (But it's cheaper to do your own with sheet goods, particularly if the roof lines are clean simple & flat.)
In a house with those R-values it's worth putting 2" of type-II EPS under the basement slab , 4-5", if it's radiant floor.
To control humidity you need to control air-tightness- caulk every stud & stud plate to the sheathing, and use closed cell spray foam to seal the foundation sill and rim joist to the inner EPS of the foundation's ICF. Caulk or foam all seams between doubled-up top plates & studs, and even foam the electrical penetrations between stud-bays prior to insulating. Then you need to ventilate in a controlled manner with an HRV or ERV (ERV is somewhat better for controlling summertime humidity.)
Wood boilers are A: inefficient and B: a local air-pollution nightmare, due to how they are usually controlled and operated. A the end of a call for heat they are instantly starved for air while hot and fully burning, which leads to MASSIVE soot emissions for 10s of minutes or longer, until it cool sufficiently. Even if the steady-state full fire efficiency is north of 80% and emissions pretty low, the smolder-out control feature takes that down by a LOT- if it averages 60% you're lucky! (By comparison an 80% woodstove sized appropriately for the heat load of the house puts out a tiny fraction of the particulates, and will usually average better than 70% efficiency even if you throttle it down to under 1/4 of full-fire for an overnight burn.)
If you're undeterred by these aspects, when shopping for wood boilers get the SMALLEST wood boiler that covers your design-condition heat load (in the house you describe even the smallest of most of them out there would be more than 2x your actual heat load), don't even look at the steady-state efficiency numbers. A 70% boiler that's actually firing is a lot more efficient and cleaner than an 85% boiler spending a higher fraction of hours running in smolder-mode.
People have been taking their neighbors to court over this, and there's a recent case in Fairbanks AK where the STATE went after a couple of wood boiler operators for violating air pollution standards:
http://www.newsminer.com/news/local...f6878.html