Indoor is where you learn the basics of airsoft, you can just wear jeans, hoodie and sport a gun with a hicap. Outdoor generally is where you should have a more advanced setup since accuracy and what you have in your loadout actually matters.
Since you're a beginner, it'd be best to stick to G&P, KWA or VFC AEGs as a first gun, so your choice is fine. They're already on the higher end of guns and don't need immediate work on internals to have them running reliably. However as for a model, you should go to a walk in store, look around and hold some of the guns because you will probably end up changing your mind.
As for getting a hold of gear, you don't need to be age verified to get it. The benefit of being age verified is that you can access the classifieds on guns and gun parts, you already have access to the gear and clothing classifieds.
Guardians of Asgaard - KF32
VFC H&K 416C
VFC KAC SR16 JL Billet SBR
TM FN Five-seveN