[A-2] I’ll open the window.
At the point of saying this, you already made the decision to open the window, since in effect you are agreeing it is too hot and you are offering to (want to) do it.
[B-1] I’m going to learn to play the guitar.
Here you have the intention to learn to play the guitar, but it is a long process and it is uncertain whether you will be successful or not. So this is a "present intention".
You are wrong to think that a native English speaker would probably understand She will be loved as She has a strong desire to be loved or She wants to be loved.
The German equivalent of the English She will be loved is Sie wird geliebt werden, not Sie will geliebt werden.
In most cases the German verb wollen (ich will, er will, wir wollen, etc) would be translated into English as want (I want, he wants, we want).
However, it is possible to interpret will in certain questions as shading more towards want or desire than towards a future action. For example:
Will you stay for dinner?
The will in negative constructions such as She won't tell me would normally be interpreted as a refusal rather than as a predicted (non-)action.
Furthermore, will can also refer to the present (habitual) in constructions such as:
She will keep phoning me in the middle of the night.
And will can be used to express probability or certainty in constructions such as:
That'll be the postman! (on hearing a knock on the door)
A good pedagogical grammar book such as Swan's Practical English Usage will help you understand the various uses of the English modal will.
Best Answer
"Expire" is a current condition that may refer to a future event, so it's acceptable to use the present tense:
Use this instead of "getting expired", which is not idiomatic.
Otherwise you can use the future tense "will expire" or the (somewhat more awkward) participle variation "will be expired".
Note that we use in for unspecified dates within a period, and on for specific dates:
[Edit] As Michael Harvey suggests, the future perfect is also an option: