I’m laying reclaimed ¾” solid pine throughout my house—a rustic look that hopefully will be somewhat forgiving. The first half of the project is roughly illustrated below, indicating direction of boards and locations of doors. (The second half will involve living room and kitchen.) Questions correspond to numbered dots:

Dot #1: The “?” indicates an area I haven’t yet decided about direction. Should I turn here in the hallway (highly visible) or continue the same direction as the rest of the hall and turn at the doorway to room #1 (risking the “ladder” look in the L of the hall)?

Dot #2. I’ll have two of these turns to do; one here and one near dot #1 depending on how I resolve question #1. I’d like to keep things as simple and clean looking as possible so my first thought is simply to butt the two together. (BTW, my reclaimed pine is not end-matched, so I’d have to use a slot-cutting bit and rout a groove for a spline, I assume?) Since expansion issues involve only the width of the hallway, is this safe to do? Or do I have to make a T-molding and allow for expansion? Or is there some better approach?

Dots #3, 4, 5. These are all transitions from wood to tile. Once sanded, the wood will be close to level with tile. 3 & 4 are definitely on the side of the board, #5 could be either on the side or the end of board depending upon how I resolve my first question. What to do with these? Again, I’d like to keep simple clean look, if possible. I’ve seen a reference on this forum to “grout caulk” (looks like grout but expands/compresses like caulk), which I’ve never heard of. Is that the solution? (And what exactly is it?) Or do I need some T-molding here? Something else?

1) that space looks square to me therefore either way is acceptable. My preference would be to keep the same direction as hallway and make direction changes in doorways.
2) You can butt the direction changes together. Reclaimed pine is quite stable as long as you maintain normal temps and humidity. You may bisquit your butts if you wish, no harm. Many glue and nail wide pine( I do ) making end matching less important. Per Carlisle Restorations
3) If you don't want to use T-molds, don't. Leave a grout joint and caulk it.