Ubuntu :: Setup Apache To Serve Only The Computers In The LAN?

I use to keep a running instance of Apache in order to test my sites locally. I'm usually not that fussy about security, assuming my 80 and 8080 ports are closed (and, well, also the other ones).Anyway this evening I was just logging into PHPMyAdmin when I found the default username was a string of garbled characters. When I entered PHPMyAdmin, I was greeted with the message

Code: Additional features have been disabled in order to work with linked tables. To find out why click here.So I clicked and it seems that the error comes from the table

Code:
$cfg['Servers'][$i]['tracking']
which has been disabled. Everything else SEEMS ok at first sight.So now I have got a few questions.

1) I checked via canyouseeme.org and the default ports are still closed. This mean it should be impossible to even try to do something on my Apache remotely, right?

2) How do I reenable the additional features?

3) How do I check if someone else logged in?

4) What about the garbled name at the login? This should be just a Firefox thing, or actually PHPMyAdmin does suggest the name of the latest login?

5) How do I set up Apache to serve only the computers in the LAN? At worst, even only the local computer would be good.