It's all outdoors (there are a very small number of rooms you can go in). So we did not notice any restrictions (though it's just common courtesy to avoid using a flash).

(2/28 1.40pm) Beijing Parks Begin Limiting Access: Though almost every park in Beijing remains open, some have started limiting the number of people entering each day. Chaoyang Park will limit tickets to 20,000 per day to control the park from getting too crowded, the Beijing Youth Daily reported. Meanwhile, tickets to the Summer Palace are no longer being sold on site and must be reserved one day in advance via their WeChat account (search "颐和园" in WeChat).

I was there the last day it was open. I would think that it will be announced when the quarentine is lifted.

The history is available online as being world history. Great place to visit very well restored and maintained.

Are you part of an organised tour? Difficult to get anywhere without an english speaking guide. It would be much more beneficial to have a guide that can answer your specific questions as the Forbidden City is massive. As for what to wear, obviously depending on the weather but there is a lot of open space with small, sometimes very crowded cover to shade yourselves. Most locals carry umbrellas.

Yes no time control.

I Will advise tour guide. He help to skip queues and show you the hot and hidden spots.

Niestety nie pamiętam godzin otwarcia, byłem we wrześniu w ub. roku. Było warto, pozdrawiam

Yes best to go during the week not on weekends

We just walked up to the ticket gate with our passports and purchased our tickets. The ticket gates are on the right hand side before the Meridian Gate Entrance. You'll see locals gathering around the small ticket offices. No problems with language either. There was a lady attempting to get us to go with her to buy tickets, saying that it is a long wait in the heat and that she can expedite the process, but this is a scam and don't fall for it. Your passports become you tickets at the entrance. As usual, there is security screening on bags and yourself before entering the ticket office and the Meridian Gate. The biggest problem we had was finding the actual entrance to the before the ticket office, from the subway station. Unfortunately, China is very bad with their signage to attractions.