It means please, but it's also an appropriate response to תודה. As in many languages, the word for "please" does double duty, so as well as "please" it can be used to mean "you're welcome" or similar. I believe it can also be used to mean something like "here you go" when you're giving something to somebody.
TL;DR: Yes, it means please, but it means other things as well.
Yes. The antwort below is from http://www.shamaileibowitz.org/2016/09/the-cold-hard-facts-of-gelida-story.html
It doesn’t appear in the Bible, but it is found twice in the Targum Onkelos, the Jewish Aramaic translation of the Torah from around 250 C.E.
In Genesis, when Jacob complains to Laban about the extreme weather conditions in which he worked for him, he says: הָיִיתִי בַיּוֹם אֲכָלַנִי חֹרֶב וְקֶרַח בַּלָּיְלָה “Often, scorching heat ravaged me by day, and frost by night.” (Genesis, 31:40, JPS translation)
And the Targum Onkelos translates:
הֲוֵיתִי בִּימָמָא אַכְלַנִי שַׁרְבָּא, וּגְלִידָא נְחַת עֲלַי בְּלֵילְיָא
The second time it appears in the Targum is in the description of the manna: "Over the surface of the wilderness lay a fine and flaky substance, as fine as frost on the ground" (Exodus 16:14) where the word "frost" (כפור) is translated into Aramaic as "גלידא." So there you have it – גְלִידָא (gleeda) as an old Aramaic word meaning “ice” or “frost.”
Through the Aramaic, the root ג.ל.ד entered the Hebrew language and found its way into Rabbinic texts, adopting another meaning on the way – to harden and form a scab or crust, as in: הִגְלִיד הפֶּצַע - the wound became a scab
Fast forward to early 20th century Jerusalem. ... Eliezer Ben-Yehuda, the chief architect of modern Hebrew, realized there’s a desperate need for a Hebrew word to describe this frozen delicacy. Based on the above-mentioned sources, he took the root ג.ל.ד and created the word גְּלִידָה:
"People who speak Hebrew in Palestine [will use this word] to call the sweet concoction made from sugar and eggs and cold as ice.” (Ben-Yehuda’s Dictionary, Second Volume, p. 1909).
How do you pronounce the word? Interestingly, Ben Yehuda wrote that the emphasis should be on the last syllable of the word (glee-da), likening it to the word לְבִיבָה (potato pancake). However, he failed miserably: Virtually all Israelis pronounce the word: glee-da (emphasis on the syllable "lee").
The word was coined by Elieser ben Yehuda, and yes, it has etwas relationship with ice. See: https://www.haaretz.com/jewish/features/word-of-the-day-gleeda.premium-1.518555 and http://www.balashon.com/2006/09/glida.html
It's לאכול you put the vav in the wrong place.
Yes, they are pronounced differently, because they are different words. אוכל pronounced "óchel" is a noun and means "food". אוכל pronounced "ochél" is the present tense masculine singular form - "eat(s)". לאכול pronounced "le'echól" is the infinitive "to eat".