I am using BM Decorators White. No reason except it's not white-white & many designers that I have read on-line have always referenced it in their work/portfolio. In real light it provides enough of a pop without being 'torch your eye' white! Sorry - that is the only words of wisdom i have & no magic formula or template. :)

Some term definitions to start. The hole for the door is called a rough opening(RO). That hole is made by installing king studs(which span floor to ceiling) and jack studs(which span floor to the top of the rough opening) and are attached to the header(top of the opening). See the link I inserted. Those chips(called shim packs) are actually the shims used to install a door frame in a rough opening to the jack studs and header and are the usual procedure. Although there are not enough of them in the pictures(unless you have already removed some). On a door like that(with 3 hinges) there should be shims at each hinge and one pack approximately centered between the hinges(5 shim packs total). And similar placings on the latch side. There seems to be a bit more to this situation. What is the line on the right side of the wall? Is that where the old trim stopped? Is the line old caulk? If I were fixing that, I would remove the sheet rock at least as far as one stud to the right of the stud forming the rough opening(called a jack stud) and replace that sheet rock to make a smooth section of the wall. I'll bet the left side is the hinge side and was situated as such for the door to open against a wall on the left. That is pretty normal design.It is also fairly normal for the left side trim to be more narrow, since it is usually blocked by the open door. You will probably need to move the entire rough opening to get the 4" you want. An experienced carpenter/handy person can do that fairly easily. It is also a DIY project for someone willing to learn. There is nothing load bearing involved, so simply adding studs to the left side(actually nailing two to the existing left hand jack stud) and removing the jack and king studs on the right (and the header) to install a new jack/king stud and header for the new RO. That will, however mean removing the dry wall on both sides of the walls and replacing with new. That is a lot of work and expense to add 2" however.

Pine is much softer than poplar, although now with the shortage of materials and price increases, you have to be careful with the poplar you get as well. Google fj pine vs. fj poplar vs. mdf to see lots of info and opinions. Here is one thread to start with: https://www.houzz.com/discussions/2584211/mdf-or-pine-baseboards-painted-white My husband & I are doing the final 3 rooms of a total remodel. We have either removed, refinished or replaced ALL of the trim - crown, base, chair rail, stairs railings & window & door casings - in a 6K sq ft house. Because everything is a "live & learn", we used a primed pine chair rail - as I really liked the profile. It is fine in the larger rooms, as it is never touched, but in the stairway it gets dinged easily. But one exception to the primed poplar, is where we had to replace some door jambs. In our experience, mdf finishes better and holds up better. The best option would have been a paint grade maple, but we have some door jambs that are 8" & 10" wide, so we had to improvise. This has been a long project (life happens), and when we started, we would use some trim from from the big box stores in certain profiles. At this point in time, we only order through lumber yards that use specific mill work companies. (In our area, that's Metrie, Ferche, Colonial Craft.)

There are too many decisions when you’re building a home (I assume it’s a new build, but even just a reno has so many decisions). Who is installing your trim? Sometimes you can have someone who is good with suggestions or can put together different profiles for you to consider. In general, you want your home style to coordinate outside and in. That’s why I asked what the outside looks like. From the windows, I am imagining something that’s more transitional - something between traditional and contemporary. It doesn’t look craftsman, but sometimes the simplicity of the craftsman profiles work well in a transitional home. Here is a guide to different moldings. It starts out very traditional, which I don’t imagine your house being. https://kelleher.com/wp-content/uploads/Catalog_Web_DesignGuide.pdf Here is another: https://www.metrie.com/the-finished-space/baseboard-styles For my personal home, I have shaker cabinets and went fairly simple with moulding. 9” baseboard with a simple chamfered top. No crown moulding. Built up window moldings (taller since there is no crown), but still pretty simple. Your cabinetry style can help inform your choices. Are yours flat panel or are those just paint samples?