How to solve problems of identity column

I work with code first technique in visual studio 2015 with entity framework 6.1.3

but i have some questions confuse so that if possible i need answer to these questions

1 - IF I have table name student and it have primary key column StudentID.

to add data to table student must StudentID column be identity or what.

2- if i have table student and column StudentID primary key but not identity

and table already create but suddenly i need to change column StudentID

to identity what i do to make it identity .

.table not have any data .

3 - if i need to start by number 1800 in column StudentID then after that

make it identity what i do

I can do answer to all question above if i do it by sql

but if i need to answer these questions from visual studio 2015

How i do