I would say that you certainly should be welcome in such a store - you are honestly considering a purchase, and have some sense of the direction that you want to take.
I would share that information honestly with the staff, and guage the reaction. If you get the feeling that they are too quick to jump to sell you some kit, you are in the wrong store. If, on the other hand, you get the sense that they take the time to explore your thoughts, and offer some ideas, and allow you to play around with some potential gear, then that is where my money is closer to being spent.
In the end, you will decide if you want to spend there, but I would suggest that you clearly are a potential customer for them, and at your age, they should be very interested in closely partnering with you... for your eventual upgrades etc.
Perhaps it is just my own years of sales speaking...