Your second question depends upon what you mean by melee. A subclass that is melee focused could simply be one that prefers melee to ranged, or it could mean one that is capable of filling the defender / striker melee role and being a member of the front lines in combat.
If you're looking for someone that can stand on the front lines, I would not suggest rogue as the class for you - at least not pure rogue. If that were the goal, I'd go with a fighter or ranger to level 5 and then multiclass rogue. Some other melee options that work as a 1.) magic using, 2.) stealthy, 3.) melee force build are: a.) Dex based Eldritch Knight with the Urchin background to 6, then Arcane Trickster. b.) Elven Bladesigner with a dex focus, c.) Hexblade warlock with a dex weapon and urchin background, and d.) wild magic barbarian that uses strength to attack, but is also dextrous. They take Fey Touched at 4 to get invisibility which you'll use before comat and either false life or disguise self... neither of which require concentration.
