Your ideas are fabulous. The only way to know the time frame and price is to start interviewing contractors. Whatever they say is the expected time to completion, add a week. Bathrooms are very complicated rooms, even if you keep all the fixtures in the same place and just make a “switch”. My 3x9’ powder room took 3 weeks. Remember, you need tile, glass, plumbing, painting, etc. Lots of different specialists to do a bathroom.

Get referrals from friends and neighbors who may have renovated their bathrooms. Save pictures of what you like and in a short while, your taste will be crystal clear. You may have to modify some things once you find out the cost of the materials and labor. A gorgeous freestanding, deep tub can run into serious money. Every decision can change your budget.
My friend redid her small master bathroom in her 1925 house. The most expensive item? The stunning marble floor tile she couldn’t live without. For her, it was worth it so she kept her existing tub to stay within budget.