for connection string, you can visit www.connectionstring.com.
for the list of the item you mentioned, let me briefly go through it as per my understanding

DB Diagram
- to design the system logical diagram
Tables
- to creat tables in DB to hold data
Views
- something like a table which you predefined for better serach performance
Stored Procedures
- consists of compiled T-SQL for better performance, security implementation etc.
Funcsionts
- user defined functions
Synonyms
- <no idea>
Types
- user can always define own types other than system defined types
Assemblies
- self defined component which is compiled and ready to be used

pls correct me for anything thats wrong