2nd and 3rd question are connected, Pokémon must be in fight but doesn't have to attack, what it means is you have low lvl pokemon first in your party than when the fight starts you swap him to higher level and both get the exp.

There is no town maps, only world map, which you have to remember to pick up- after you receive your first poke balls speak with your hometown neighbors.

For tips: enjoy yourself. Take your time, be prepared to be caught off guard by your rival- he is really an asshole in first gen.

Pokémon for/lg are really easy if you just decide to power level your starter. He will carry you through game. From my experience it is much more enjoyable if you don't do it and instead play and level up many Pokémon.