1: There's lots of people running around with cameras, as long as you do it somewhat discrete and don't mess up other peoples immersion and roleplay I guess you'd be fine. As long as you're not doing the "battlefield tourist" thing, at least.
2: Several shops sell coins you can use ingame. Word of advice unless you plan to play stinking rich and engage mercenaries and such is to buy copper. As the price of copper, silver and gold are roughly the same pr/coin many player merchants like teahouses and such prefer to be paid in copper. Some even refuse to accept silver or gold.
3: Yes, you get 15 square meters for each person in your group, but it is camp area not tent area, if you plan to have space to sit, cook or whatever outside your tent you need to use of your groups alloted space.
4: Spellcasting normally requires both hands free and are limited to tier one armor (leather/cloth).
(Metal armor renders you unable to cast spells)
5: Nerf guns are allowed as long as they do not fire any projectile, they fall under the special ranged weapon rule:
Special ranged weapons just for the ambience
To this category belong all sorts of ranged weapons that cannot be classified by
the categories above (e.g. Bandguns, Pirate Pistols with blank cartridge (and no projectiles), Nerfguns and so on).
The emphasis of such weapons is on the ambience and not on the damage they cause.
Decorative firearms must not be able to fire projectiles.
Such weapons can only be used once in a battle, do 0 Damage and only inflict an
effect like „Gust of Wind“ on the target, which takes the target back a few steps.
Freedom and explorer are probably best if you are new to the setting and not connected to some larger group.
You might want to look up "the Grand Expedition"; an international (english speaking) group open to anyone willing to follow its rules and character concept limitations. Both plotters and fighters call the G.E. home, and you'll find lots of experienced players willing to help exploring the Mirrorworld.
The G.E. are most likely staying in the Adamant banner/Western ward, although aligned with the elements the G.E. does not require the individual characters to worship the elements.
If you are interested in joining up, send me a PM and I'll direct you to the group leader and page