I've often said going to the Olympics is unlike other trips. Usually, you plan out a trip, then decide if you want to go or not. With the Olympics, you decide "I want to go," then fill in whatever details you can get. Are you wiling to take that leap of faith.
One thing people might not realize is how much of the "Olympic Spirit" does not involve going to events. As much as I love going to events, they can be a real pain. Lots of logistical headaches, lots of security to deal with, lots of waiting around. Many times is better to watch an event as a bar or "live site" than at the event itself. And, yes, watching in a bar in the host city is different that watching at home.
Of course, you do want to go to some events. Of the events you list, Opening Ceremony tickets are very hard to come by. You might get them, but certainly don't count on it. Basketball prelims are usually available at some point, the gold medal match (mens) can be hard. 3x3 basketball tickets keep popping up, so I suspect that will be easier. Hockey is one of the easiest tickets to get. Football is the only sport where I can guarantee you'll be able to get tickets... though no guarantees on the gold medal match. Swimming and Women's gymnastics are some of the tougher tickets to get (and some of the sports that are much better on TV than in person). Beach Volleyball and Men's Handball are usually available.
As far as planning, the first thing I always focus on in whether to target the first week or the second. That way I can book tickets and travel plans independently. Think about which events you most want to try for, and then look at the schedule to see when they are held.
Lots of accommodations will have minimum stays, required deposits with no refunds. Always nice if you can book someplace that will be refundable, but don't count on it. As I said, you basically need to commit and just go for it. Mainstream hotels will either be completely book, or outrageously expensive. If you want to stay in one of those, either pay the $$$ or wait until the last month or so when they will inevitably free up rooms. The freeing of rooms happens every olympics, but I've never had the guts to wait. I always target non-traditional housing - hostels, dorms, airbnb, etc. Tokyo offers up another option in "businessman" hotels. Finally, there is always the operation of booking something out of town and commuting in. Tokyo has incredible train options for that.
Plane tickets is usually the easiest thing to book. Mainstream airlines open up about 330 days ahead of time. Unlike hotels, they don't jack prices sky-high. Just don't count on a deal.
Best of luck.