3) will for present habits:
There is no question that the verb (or verbs; there may be several) will is one of the very trickiest ones in the English language for foreigners ever to master. The deontic senses are seldom intuitive to a non-native speaker. I strongly advise you to carefully study the OED’s entry for this word’s incredibly many subtle uses.
In this case, your two examples are not of the same thing at all, and you have mischaracterized them. The first uses will to express habitual action; it does not indicate a simple future situation. This is the OED’s sense 8 for this verb:
8. Expressing natural disposition to do something, and hence habitual action: Has the habit, or ‘a way’, of ––ing; is addicted or accustomed to ––ing; habitually does; sometimes connoting ‘may be expected to’
This is related to sense 15, which is still not a simple future, albeit perhaps closer to that:
15. As auxiliary of future expressing a contingent event, or a result to be expected, in a supposed case or under particular conditions (with the condition expressed by a conditional, temporal, or imper. clause, or otherwise implied).
Your second example, the one about the car, is completely different. This corresponds to OED sense 12:
12. With negative, expressing the contrary of senses (def#6), (def#7), (def#10), (def#11): thus commonly = refuse or decline to; emph. insist on or persist in not --ing. Also fig. of a thing. (See also (def#9), (def#13).)
Here, your car is persisting in not starting. It is the figurative sense at the end extending to things, as though they had the will to refuse. The referenced senses 9 and 13 are respectively:
9. Expressing potentiality, capacity, or sufficiency: Can, may, is able to, is capable of --ing; is (large) enough or sufficient to.
15. As auxiliary of future expressing a contingent event, or a result to be expected, in a supposed case or under particular conditions (with the condition expressed by a conditional, temporal, or imper. clause, or otherwise implied).
As I said, will is quite complex. Please study standard reference works regarding its use.
Can we interchangeably use "to be in for", "to be down with" and "to be up to" ?
"To be in for" and "to be down with" are more similar to each other than they are to "to be up to."
When I ask you, "Are you in for the show tonight?", I mean, "Are you in the group of people who are going to the show tonight?"
When I ask you, "Are you down for the show tonight?" that could be short for "Should I put your name down on the (metaphorical) list of people going to the show tonight?"
"To be up to" is used almost exclusively in the present tense. "What are you up to right now?" is much more common than "What will you be up to later tonight?"
"What are you up to?" should not be confused with "What are you up for?"
- "What are you up to?" = What are you doing right now?
- "What are you up for?" = What would you be interested in or what do you feel capable of doing?
Best Answer
I don't know whether you're native English or not, but in the UK, we would never say 'put my children to sleep'. What that actually means is you're intending to either kill them, or use knockout drugs to make them sleep. We put animals 'to sleep', which is a euphemistic term for killing them, in particular with the use of drugs, when they're ill or suffering. Therefore, 'put my children to bed' is usual.
As for switch and put your mobile ... either is fine.