You can find Roblox user ID number from your profile URL. Roblox User ID can only be accessible from PC or Mobile browser URL. Roblox player ID used to quickly find your player profile in game.
No, You can not play Roblox offline. There are many reasons for that which are given in this post.
This post includes a guide and FAQs about Roblox promotional codes (Promo Codes). You will know about the latest promo codes, how to redeem promo codes steps and get answers for related FAQs.