Planning to install 3" wide 3/4" engineered oak, floating on a concrete floor. About 1100 square feet total, see diagram attached (areas in blue). Some questions:

1. with this large of area, are thresholds (T Moldings) recommended to break up the area? I'd just assume not have them, but can live with them if I would be better off. If needed, do I need them at locations A and B (28" doors), or C as well (60" double door)?

2. With or without the thresholds, any suggestions on the best direction for the flooring "1" or "2"?

3. There is a sliding door to the outside on one wall (not shown, but it is on the wall to the right of the fireplace near the top of the drawing). The base of the door is a metal track that is going to be significantly lower than the 3/4" floor (plus underlayment). How do you finish this? Would a "reducer" molding do the trick? If so, does that influence the direction of the flooring (use direction "2")?

Thanks in advance!