How long takes panning the 3-4 minutes long song? Do panning and mixing are the same thing?

Panning and mixing are not the same thing. Panning is one part of mixing, but mixing also involves level balancing, and all sorts of audio processing. Panning is specifically the positioning of different tracks in the space between stereo speakers, to create a nice wide soundstage that can help provide better clarity in a busy mix. How long it takes to mix a song depends on the song, the tracks, the arrangement, the engineer/mixer, any deadlines [for commercial projects] -- it can take anywhere from a couple of hours to a couple of days.

Speakers and headphones I need only for panning but not for mixing? If so, then is no need to buy them if I will buy panning from any music engineer. I mean, I put to google mixing services and got the results, where an average price is 20€ per hour. You write that mixing itself takes from couple of hours to some days, but if it's only panning what I need, does it take less than hour.. ? i mean, how much the panning could cost to me.. ? If it's a work about an hour, no problem..

Panning is positioning the different tracks in a musical arrangement at different points between the left & right speakers or headphones. It could take you 5 minutes to to simply pan all the tracks in a small arrangement with only a few tracks, but usually it would be a larger part of a more complex mix of a song with many tracks, where you creatively devise a well-balanced stereo image with a combination of simple panning, doubling, and the use of stereo effects. The processing that's applied in a mix may change depending on how the tracks are arranged in the stereo image, and the decisions that go into determining the panned locations of the various tracks may be informed by the way the musical parts blend as the mix is gradually built up. To me, panning is an integral part of mixing, but mixing can be a complex process that involves many different aspects, including static & dynamic level adjustments, technical processing, creative processing, and stereo imaging [panning]. It seems to me that focusing on the idea of panning as some kind of isolated thing to do misses the point of that.. You could mix a song while monitoring [listening] on anything, but if you plan to distribute it to the public in any way, and want it to sound like a professional production -- including for those who may listen to it on proper speakers & headphones -- then you'd really need a proper listening environment when mixing. However, if you're not really concerned about that, or if you're not ready for [or interested in] building up mixing skills at this point [which would take time and practice], then I guess you could hire someone to mix the tracks -- obviously many people do that, that's why those mixing services are available. It's all up to you -- I don't know what your musical arrangements will be like, whether you plan to distribute them to the public, or how important it is to you to have professional-sounding mixes, so I can't tell you what to do..

OK. Do I need speakers and headphones only in panning, or do I need them yet in any other mixing operations?

It's always recommended that mixing be done listening (monitoring) on speakers, and the mix also checked on other speakers and headphones, to see how it sounds on a variety of playback systems. The idea is that the mixer can get a decent idea how the mix will sound to different listeners, something important to anyone who plans to distribute their music to the public.

You write that mixing would be done using the speakers and headphones. And you say that mixing also involves all sorts of audio processing and level balancing besides the panning. Am I understand rightly, that all these mixing operations I described now, need speakers and headphones.. ?

Yes, all aspects of mixing would benefit if the mix was done on a decent pair of studio monitor speakers [or at least a decent set of headphones, though speakers are better]. As I said, a mixer who wants to be able to create the best possible mix for anyone who may eventually hear it would want to mix on a decent playback system that provides a reasonably accurate picture of what the mix actually sounds like. Of course it's possible to mix on anything, but if I were mixing something I would never want to rely on just the sound from the built-in speakers in a laptop to do the mix. But of course you can mix on whatever you want -- if you're happy with what you're listening on, then I guess it doesn't really matter, it's up to you..

OK. But mixing and automation are two different things. Does automation need also speakers and headphones or can I automate my song only with garageband? And automation first and the last thing what I can do with my song, that's the mixing, right?

No, this is not correct. Mixing includes pretty much everything except the actual recording of tracks and the arranging and editing you do with the Regions. Mixing includes balancing, panning, processing, and automation. Automation is an optional part of mixing -- if while you're mixing you decide that some settings (like the levels of some tracks or other effects) need to change over the length of the song, then you can use automation to create those changing levels. If changing settings aren't needed for a particular mix, then no automation is necessary. You could apply automation to a mix at any time during the mix, but you'd have to set up the mix first to determine if there are settings that may need to change throughout the mix, so often it may be added closer to the end of the mix, for fine-tuning of a mostly-finished mix.