@Sandeep1 - I *highly* recommend the Disneyland Hotel! It is so, so beautiful! But, in full disclosure, it is still a good walk to get to the park - probably comparable to walking from Boardwalk to Epcot, but not nearly as far as walking Beach Club to DHS. However, they do have busses.
Every time I post about staying at the Disneyland Hotel, I encourage people to consider Club Level if their budget can afford it. If in-park dining (like at the castle) isn’t a high priority for you, the food in the Club Level Lounge is some of the best I’ve had in a Disney Park. They have Western dishes/foods, and they have very interesting Asian dishes. The fruit was outstanding (as I found it was pretty much everywhere in Shanghai). So, if you want to try some new foods, it is a great opportunity. Plus, the service is top-notch! And for us, traveling with three boys, the cost worked in our favor. I think we only ate one meal - lunch - in the park! We tried some of the snacks, of course. My husband, who is a low-maintenance, no-frills kind of guy, LOVED it and would go back just to stay CL!

Whether or not you decide to stay CL, make sure you keep checking hotel prices as they do tend to go down the closer your stay.
I think in a low crowd season, two days will be sufficient. If on your first day you aren’t able to ride as much as you wanted or the crowds are heavier than expected, you can add the Premier Pass on just your second day. I know that $17 a ride seems expensive (and the PA Set averages lower cost per ride). I felt the same way before we went. But when lines get up to 2 or 3 hours long (and in our case 5-6 hours long because we were there on a holiday!

), then you have to consider the value of your (limited) time in the park. Also, it is demand-based pricing. You won’t really know how much it costs until the day-of. I believe I found that if you wanted to ride more than three of the Premier Access rides, you might as well buy the PA set. Also, I’m sure you know they dohave FastPass kiosks, and if it’s a slow day you may be able to just FP some of the rides.
Finally, you said you would be visiting Shanghai proper as well. I highly recommend checking into UnTours. We did the dumpling tour and it was FANTASTIC!!! The price was very reasonable. Yummy food as well as learning about the “history” of the foods. We had a wonderful, knowledgeable tour guide. And, we got to walk around the city and see some of the different areas.
We also did a private one-day tour to a water town that was recommended by another DIS-er. It was fabulous! Again, it was a little pricey, but in the end, we absolutely got our money’s worth out of it! If you want more info on that or UnTours, PM me.
I hope this helps and that you have a wonderful trip!