Can I delete these Logic Studio applications?

You could..but frankly I'd keep them.....

In particular ST Pro and Waveburner which are much sort after and much missed apps, by those who never bought the Logic Studio package in the past... If you have never used them you might want to take a look/see what you are missing.

Node, if you never used it, you can delete... but its tiny so it wont save you much space...

Mainstage, if you have no intentions of performing live, you could delete to (and as there is a much newer version in the App store.. you would probably want to upgrade to that newer version anyhow if you wanted to perform live)

Codemeter isn't anything to do with Logic Pro.. It's a 3rd part app... that you must have installed in the past.

http://www.codemeter.de/us/service/downloads_mac.html

Apple Qadministrator & Apple Qmaster are part of the load sharing stuff....across multiple Macs on a network... Your choice to keep or dump.

Deleting just the apps.. won;t affect any loops, samples or instruments... and just deleting the apps themselves wont affect anything else...

However, again I'd recommend keeping (Unless you are extremely tight on free space) at least;

ST Pro,

http://en.wikipedia.org/wiki/Soundtrack_Pro

Waveburner

http://en.wikipedia.org/wiki/Waveburner

and finally Compressor...

http://en.wikipedia.org/wiki/Compressor_(software)

but as always, it's your choice..