You appear to be new to Filemaker Pro and are likely new to creating databases also. We'll help you all we can, but you may need to invest some time in learning more about Filemaker Pro and databases. There are books you can read and tutorials available that can help you increase your basic understanding.
"I have 2 databases which have contact details on. How can I set up a view which allows me to view a list of names of people from all the different companies collectively from both dbs?"
I can't help you much here as I have no real idea as to what exactly you have set up here. Why two databases? Do they contain exactly the same types of data? Are they the same structure? Same database application? and so forth. If possible, you would be better off to import all the contact info from one database into the other. I can't begin to tell you if that is possible or practical from what you've posted here.
"Also would I need to set up a network between me and my boss for us to both use the database at the same time? & would we have to buy the software twice? one for his comp and one for mine? "
That depends. If you use Filemaker's Instant Web Publishing, you could publish your database to the web and your boss could use an internet browser to view and edit the data. IWP has its quirks and limitations, so you would want to study up on this concept to see if it will work for you or not. If you don't publish to the web, then both computers would need to be networked and you'd need two separate copies of filemaker to simultaneously access your database.
"One more. I would like to make a comments field with a drop down calendar which allows me to type in the field too, or would it be easier to just use a text field and manually type the date in? "
While you can do this quite easily, I wouldn't recomend it. I would be a better set up in almost all cases to create two fields. One field would be your date field and one field would be your "notes" text field. Keeping two different types of data in separate fields will make your data much easier to work with.