So can be used to say that another subject is doing something "as well" or "in addition." - you can keep things in one sentence with so but not with as well or in addition (so that's why it happens in speech often):
Vinay plays cricket, and so does Ashok.
Vinay plays cricket. Ashok does as well.
But if there's a second action, so takes on the meaning of because of that:
He can speak French, and so can speak German.
He can speak French and because of that he can speak German.
Don't use so at all, simply say
He can speak French and German.
The problem with this:
I seldom went to Christmas parties, neither did he.
is that while "seldom went" has the meaning does not go that often, it's not a verb in negative form, so neither doesn't correctly link back to it.
You can either change "seldom went" to a negative verb, add "he" to the subject of the sentence, or make "neither did he" a full sentence with "either". ("Seldom" is one of those words you generally don't want to overuse by using it in two sentences in a row.)
I didn't tend to go to Christmas parties, neither did he.
He and I seldom went to Christmas parties.
I seldom went to Christmas parties. He didn't usually show up to them either.
The question seems to focus more on religion than on sports or hair style.
A religion is a practice not a belief. You might not believe religions exist until you see people go to a place of worship. So religions are a fact, not a belief. They do exist.
However, a religion's followers share their beliefs in theological matters.
So if you see someone reading a holy book, pertinent questions might be
Do you follow a religion?
Do you practice a religion?
Which religion do you follow?
But if a conversation has given you a hint that it may be so, you can ask
Are you religious?
I would not use that as an opening line for a conversation, it needs to be led towards by "small talk" to get a conversation going, unless you have an encounter with someone reading a holy book.
I realise I have side-stepped the question about "a" or "any", because I would not say it like that at all, and I hope this answer helps.
Update:
In the second case, I think you can say "a team" or "any team".
The third case is harder.
Is there a girl with weird short pink hair at the party?
This implies you have seen or know the girl and want to know if she is at the party.
Is there any girl with weird short pink hair at the party?
This means you want to meet such a girl and ask if there is one like her at the party.
Best Answer
In spoken English, object pronouns are also used as emphatic or referential pronouns.
For example, I typically think of myself as "me," and a group including me as "us." We use these emphatic or referential pronouns in any stand-alone statement (i.e. one without a verb), such as a quick answer to a question.
Thus "who wants to come?" You could say in response "Me." "Us." "Not us." or "Her" or "Not us, but maybe them." (note that with "you" there is no ambiguity since the subject and object pronouns are the same.) Saying "I" or "we" or "they" or "she" is ungrammatical. Saying "I do" or "they don't" is fine but is not what most English speakers would do.
In prescriptive grammar, this is frowned upon. Hence, for instance, you can find scorepads for card games labeled "we" and "they." In my opinion this style of speech sounds very unnatural. Unless you are writing a formal document, you should aim to talk like the child in the movie, if your goal is to sound more like a native speaker.
Similarly, in response to "Who's there?" "That's me." Or when a stranger calls you on the phone and asks "Is Sarah there?" If you are Sarah, you say "that's me." (Prescriptivists will tell you to say "this is she," but this again sounds extremely formal.)