I'm not sure where you are with this, but before spending loads more money, go to some shows, read loads of threads on here and work out what it is that you want from a layout. Do you enjoy watching trains circulate? Do you like shunting? Do you get more pleasure from finding the tiny details that people put in?
Also, how much time do you have to put into it? How much money? Are you a skilled scratchbuilder or are you like me and struggle to build a box from a kit? Make sure your eventual design is something that you have the capability of building, our you'll get overwhelmed and end up with a shed full of dissatisfaction.
Maybe you've already done that, but once you've worked out what you want from your layout, then it's time to decide which tracks go where.
To my eyes, your plan looks very ambitious got someone who hasn't been involved with the hobby for 45 years.
Other opinions are available. I'm only newly retuned myself...