Hi Amar,

Here are some of the points for your questions:

(1) Tab creation for Custom Object:
      After creation of Custom Object is done, if you go to Setup --> Build --> Create --> Objects, you can able to see the object which you created and click on that object.
     Here you will get a Page Layout, click on the Page Layout and edit it. It will take you to the Page Layout modification where you can select whatever the fields you want to diplay on the Page when you select the Custom Object's Tab.

Page Layout:

Page layouts control the layout and organization of buttons, fields, s-controls, Visualforce, custom links, and related lists on object record pages. They also help determine which fields are visible, read only, and required. Use page layouts to customize the content of record pages for your users.

Below are some of the links on Page Layout:

https://help.salesforce.com/apex/HTViewHelpDoc/HTViewHelpDoc?id=customize_layoutoverview.htm

https://help.salesforce.com/HTViewHelpDoc?id=customize_layout.htm

https://help.salesforce.com/apex/HTViewHelpDoc?id=customize_layoutcreate.htm&language=en

https://help.salesforce.com/HTViewHelpDoc?id=customize_layoutassign.htm

https://help.salesforce.com/HTViewHelpDoc?id=customize_layoutcustomize_pd.htm

(2) Visualforce Page:
                    If we are not able to achieve certain feature using the Standard out of the box configuration thats where we will go with Visualforce Page and below are some of the example on Visualforce Page.

Visualforce is the component-based user interface framework for the Force.com platform. The framework includes a tag-based markup language, similar to HTML. Each Visualforce tag corresponds to a coarse or fine-grained user interface component, such as a section of a page, or a field. Visualforce boasts about 100 built-in components, and a mechanism whereby developers can create their own components.
 

<apex:page>
  <!-- Begin Default Content REMOVE THIS -->
  <h1>Congratulations</h1>
  This is your new Page
  <!-- End Default Content REMOVE THIS -->
</apex:page>

https://developer.salesforce.com/page/An_Introduction_to_Visualforce

https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/

https://resources.docs.salesforce.com/sfdc/pdf/salesforce_pages_developers_guide.pdf

https://help.salesforce.com/apex/HTViewHelpDoc?id=pages_creating.htm

https://www.youtube.com/watch?v=0Z4KTh1woCU

https://www.youtube.com/watch?v=9qL-fh-h1DU

https://www.developerforce.com/guides/Visualforce_in_Practice.pdf

http://www.salesforcetutorial.com/visualforce-creating-simple-page/

http://www.sfdc99.com/2015/02/20/example-how-to-write-a-basic-visualforce-page/

Please do let me know if it helps you.

Regards,
Mahesh