Am I freeloading at my LBS?
Spending $30 / month at your LBS seems perfectly reasonable. Your LBS is grateful you buy from them instead of from Amazon.

If you sometimes go to your bike store just to talk, that probably OK, as long as you are not distracting any staff from real work or keeping them from serving customers who are paying. Either they actually like chatting with you or are willing to humor you to keep your $30 /month, possible larger custom in the future and to maintain their reputation as a friendly, helpful store.

The example you gave about putting disk brakes on a 90's Hardrock frame - yeah, they were absolutely correct about that! They were not just trying to sell you a new bike.