Both uses of the past form are possible. Some grammarians speak of the past form as "remote", because it "removes" the verb to a distance which may be either temporal or social.
Hi, Maria, I'm calling because I wanted to take you out for dinner.
Here you use the past form to make want less demanding. The remoteness is social.
Sorry I couldn't track you down last night. I wanted to take you out to dinner.
Here the primary sense is clearly temporal remoteness. You could, however, work in a degree of social remoteness by also employing the progressive construction, which in this case would have no implication of imperfectivity - it would just be a further distancing device.
Sorry I couldn't track you down last night. I was wanting to take you out to dinner.
Note that this last construction could also be used in the first example:
Hi, Maria, I'm calling because I was wanting to take you out for dinner.
In this particular instance, however, the progressive construction would probably not be used because it clashes with the progressive calling in the main clause.
- Grammarians give this the Latin name horror aequi, "the
widespread (and presumably universal) tendency to avoid the use of
formally (near-)identical and (near-)adjacent grammatical elements or
structures" (Rohdenburg).
You'd be more likely to use it in a context without a prior progressive:
Are you by any chance free tonight? I was wanting to take you out for dinner.
To express the "see-what-you're-missing" sense in English you would employ a construction with a stronger sense of intention. The past would be necessary in this case, rather than optional, because you would be speaking of a prior intention which no longer holds:
I was going to take you out for dinner, but I've changed my mind.
You are right about context and intonation playing a very important role in these sentences.
If you ask a taxi driver to hurry because you are in hurry by saying "Will you hurry?" you are actually asking the driver's willingness and will hurt his/her feeling.
If you are stuck in traffic, asking the driver if he will hurry may indeed hurt their feelings, since it seems obvious that their willingness to hurry is not questioned by the fact that they are simply unable to hurry. (Albeit that some drivers have very original ways to enable them to hurry even in very busy traffic, and that their willingness to do so may increase after the promise of an extra financial reward...)
Indeed, the use of "will" normally inquires directly about a person's willingness to perform a task, and we normally assume that the person is able to do so. Asking them if they are willing when they are obviously unable might be insulting. On the other hand, you could use "would" for a hypothetical situation: "If you knew Spanish, would you help me with my homework?"
"Could you ~?" is usually more polite than "Can you ~?" but only when you ask for help "Can you help me?" is more considerate than "Could you help me?" because when the answer is no the person feels more easier to say no.
"Could" is indeed usually more polite indeed. Where "can" simply asks whether the person is capable of doing something (and implying that you would appreciate they did it!), when you use "could", you are implying that they have to also have a willingness to do it.
So indeed "could you provide an example?" is more polite than "can you provide an example?", but can is the correct form to use when you are genuinely wondering if the person is able to do something:
Can you come to the dinner party this evening? => Are you able to make it, or have you another appointment?
Could you come to the dinner party this evening? => It would be much appreciated if you would come.
"Would you mind ~?" is not polite way of asking but it's rather cynical.
It is actually a very polite way of asking. "Would you mind giving me a hand?" is more polite than any of the previous forms.
However, exactly because is is so polite, it is often too polite in most circumstances! And because of that, it can be very effectively used in a cynical way, in the same way we can use formal forms of address or other (extremely) formal language.
As such, nobody will think of cynicism if a lady asks a stranger:
Would you mind helping me cross the street?
But if I address a friend of mine in this way:
Miss Jones, my dearest, smartest friend, would you mind terribly if I were to decline your kind invitation to your extremely interesting lecture on the history of quilting in 1970's rural Northumbria?
I am quite sure she, and anyone who heard it, would understand that I might be a bit cynical about the interest in the subject as well as my actual appreciation of the invitation - and most importantly, it would be understood I am not actually inquiring whether she would mind my rejection, I am assuming my rejecting should come as no surprise to her!
Best Answer
There's nothing at all wrong with the "I want to make sure that" part of your sentence; the part that I find a bit obnoxious from a politeness aspect is the passive construction "it would be appreciated." You'd be much better off expressing your appreciation directly rather than simply allowing for the possibility that some unknown object somewhere will be gratified:
(There are also a few other minor things that I've tweaked, particularly the placement of "that" in the first phrase, and the use of the singular pronoun "it" to refer back to the plural "arrangements".)
There's a bit of a disconnect in that you've specified that you care only about the dates but then you go on to explicitly request cost information as well; but if you've mentioned the cost aspect prior to this sentence, it's not a problem.