1- at bases, airlines have a crew reporting centre usually with company mail, human resources, printing, managers, sometimes canteen facilities. Elsewhere, crew go straight to the aeroplane with their IDs and paperwork is brought to the aeroplane.
2- varies greatly. Yes
3- not unless it is a base
4- most drive in in uniform. Some fly in dressed variously, usually in uniform
5- 'I'll fly first leg, you do second, then we'll swap for the way back' or 'weather in xxxx dodgy- I will fly out, you back' etc.
6- Usually not more than once a month at most on a big fleet. Multiple short trips- sometimes a couple of times a month. Sightseeing? Not often. Heard of time change. It's not a holiday, it's work. usually 24 hour nightstops to get same flight back. Take work away, reading, visit favourite bars or restaurants, watch TV, pack up and get dressed. You have to conserve your energy for work, not tourism.
Outsiders can never do this without a lot of research for authenticity- it never sounds 'right'. Good luck, but maybe you should steer clear of the crew angle and go for the passenger side.