Some questions ... xoxoxo

I have a big app, it uses a lot of bootstrap tabs.
In Pinegrow, I cannot see the tabs at all, it does not matter where in the bootstrap hierarchy I click.
How can I see what the tabs will look like?

I cannot see where I can select - or drag drop - different classes. I have to know them all.
How can I select different classes?

The HTML for this project is over 1200 lines. HTML Only. Javascript is in external JS files, as is CSS.
I would like to break down the HTML into several files and have them merge somehow when I build.
How can I merge files?
Do you offer any kind of build?

I’ve been using Netbeans for the project - and it actually works well.
Are you guys a Javascript IDE, or am I doing Javascript in Netbeans still?