Its what I describe here as:
" spawns that are capturable by one team by capturing flag or building CP " . I made them separate point because as long as the room is not a spawnpoint there are no rules that denies shooting any weapon in there. Bremen CP spawn & goldrush near bridge spawn & braundorf CP & frostbite CP spawn & snatch CP spawn & fueldump CP spawn (& ... ) are all just empty rooms as long as CP is not built or it is built but destroyed.
So both of you exampled spawns, as long as they can be captured only by 1 team by building CP are free to shoot indoors as long as CP is not built and enemy does not have spawnpoint there. As soon as CP is built and allies can spawn there you cannot shoot mortar inside AND cannot spawnexit with mortar but you are free to use any weapon inside or camping exit.
Well. There are ways to the objective without passing enemy spawn. Thats why that rule can be enforced and makes more sense. Attacker usually has a chance to choose their route to objective and to evaluate if spawning enemy can cause harm or not. Defender has mostly no other option than to spawn there. It is balanced in its unusual way.
Yes. Spawn is the room where you spawn and spawnexits are the doorways outside from that building. 2 in front, 1 upstairs and 1 in the back.
With mortar there is usually (at least for me) common sense in play - if player can see where mortar is landing and can choose to go same direction but avoid mortar then its not on spawnexit. As soon as player is exiting the spawn and has no other option after seeing mortar than go back in spawn then we call it "mortar on spawnexit" and do not allow it.
If you know basics, then you should live long an prosper. As soon as you go exploring gray areas, there fingers can be burned.
And as in life in general - it is not black and white. No 2 situations are the same. For example. Oasis. Panzerplayer passes spawn accidentally in the middle of passing will fire it (and maybe kills himself/herself) and no harm is done to enemy - we are not gonna kick or mostly no even gonna warn as we can see - it was accident. But if someone shoot it in or into spawn on purpose, it can cause warn or even direct kick - depens who it was, what was the damage etc.
Best thing to do when rules are broken by accident is to apologize. Kick or warn or ban is not automated but given out by one or multiple people who can see the situation very differently from the player in question and without added info will make some judgement. 99.9% those judgements are valid and correct.
Hopefully cleared all your questions, but if you want anything else explained or discussed - let me know. I can say and @Eagle_cz can confirm how rebellious I was and sometimes still am about some rules or habits that we have in server. But I have understood and accept them and will stand for them because they have been put together based on long observation, experience, common sense and discussion.
C#