Is it possible to add VF page or HTML page in Salesforce setup/configuration? For examle, add a page in Administrion Setup

I'm using Decimal round up, but it seems it always give me the round-down integer but not the up-integer.

Decimal pages = this.processedNum/pageSize; 
          
this.totalpages = (Integer)pages.round(System.RoundingMode.CEILING);

processedNum = 56;
pageSize = 10;

The excepted totalpages should be 6, but it returns 5..

Any wrong with my code?

Thanks

Assuming there're User1, User2 and Administrator in the org, can Admin see the data of User1 and User2? How about in API access level, if Admin executes API query, is all users' data queried?

Another question: is the data between User1 and User 2 isolated? That's user1 can't see user2's data?

We have a app that written with Visualforce pages and Apex controllers, when we publishing it, is there need to wrap it as a Connected App? There's NO the need I think. 

Another question is, when should use Connected app? What kind of scenario is?


Thanks

Is it possible to only refresh a page block(not the whole page) after click the commandButton?

I know we can use "rerender" to render a page block, but along with "rerender",  the whole page is refreshed. That is not i wanted.

I read the developer guide of VF, it describes commandButton as:
"The button executes an action defined by a controller, and then either refreshes the current page, or navigates to a different page based on the PageReference variable that is returned by the action."

It seems the "refresh" action must be happened once use commandButton.

Is there any away to avoid refreshing the whole page?

I researched a lot and didn't find any solutions, so far I only can add VF pages to record Detail page. I saw there was a Salesforce idea posted for long time  https://success.salesforce.com/ideaview?id=08730000000Br8CAAS , but it seems Salesforce still doesn't support this.

So is it possible to add visualforce page on record Edit page now?

Can I deploy Java application to Force.com platform? Now it seems only support writting Apex codes in the platform...

I researched a lot and didn't find any solutions, so far I only can add VF pages to record Detail page. I saw there was a Salesforce idea posted for long time  https://success.salesforce.com/ideaview?id=08730000000Br8CAAS , but it seems Salesforce still doesn't support this.

So is it possible to add visualforce page on record Edit page now?

Is it possible to only refresh a page block(not the whole page) after click the commandButton?

I know we can use "rerender" to render a page block, but along with "rerender",  the whole page is refreshed. That is not i wanted.

I read the developer guide of VF, it describes commandButton as:
"The button executes an action defined by a controller, and then either refreshes the current page, or navigates to a different page based on the PageReference variable that is returned by the action."

It seems the "refresh" action must be happened once use commandButton.

Is there any away to avoid refreshing the whole page?

I researched a lot and didn't find any solutions, so far I only can add VF pages to record Detail page. I saw there was a Salesforce idea posted for long time  https://success.salesforce.com/ideaview?id=08730000000Br8CAAS , but it seems Salesforce still doesn't support this.

So is it possible to add visualforce page on record Edit page now?