Oh man, those are a lot of different questions.
Let me try to answer some of them.
Forms are used to enter data into your database, and also to display some information. One way of looking at a form is actually called the Datasheet View, which does resemble a spreadsheet.
You sound like you are approaching Access with Excel in mind. However, it is quite a different beast, and I can only urge you to forget about Excel when you are dealing with Access, even though raw tables may look like spreadsheets. They are not.
In fact, are you sure you need a relational database, or might you be better off [continuing to work] with Excel?
As for form portability, when you start a new Access project, forms and data tables are together in one file. However, once an application is working, it is often split into a part called "back end" that holds the tables, and a part called "front end" that holds the forms, queries, reports etc. The back end is typically placed on a network drive, and all the people who need to work with the database get a copy of the front end on their computers. That way, you have only one set of tables, but several copies of the forms.