Does it mean that there is only one Allah? Like there is only one Sun in our Solar System.
Yes. That is exactly what it means. There is only one Allah. If you were to read the rest of the quran and understand it (which unfortunately you cannot) you will get the same message over and over again.
Or does it mean that Allah cannot be concieved of having any attributes that ties him down to any portion of time and space? In other words, can he be concieved of being anything that is a human creation, physical or imaginary?
No, that is not what that ayah means. These might be points that we can discuss, but that ayah does not say or mean anything of this sort. It is simply a figment of your imagination.
Or does it mean that Allah cannot be concieved of having any attributes that ties him down to any portion of time and space?
Which attributes are you specifically talking about?
Or that he cannot be concieved of as having any physical or emotional attributes that we ascribe to humans?
Read this translation (not the complete ayah)
002.255
YUSUFALI: Allah! There is no god but He,-the Living, the Self-subsisting, Eternal. No slumber can seize Him nor sleep.
PICKTHAL: Allah! There is no deity save Him, the Alive, the Eternal. Neither slumber nor sleep overtaketh Him.
SHAKIR: Allah is He besides Whom there is no god, the Everliving, the Self-subsisting by Whom all subsist; slumber does not overtake Him nor sleep;
Couple of physical human attributes have been mentioned specifically which cannot be attributed to God. If you can point out similar ayahs of the quran where human emotions are mentioned as not being attributes of Allah then we can discuss further. Please keep your imagination out of it.
Here is the last ayah of surah fateha
001.007
YUSUFALI: The way of those on whom Thou hast bestowed Thy Grace, those whose (portion) is not wrath, and who go not astray.
PICKTHAL: The path of those whom Thou hast favoured; Not the (path) of those who earn Thine anger nor of those who go astray.
SHAKIR: The path of those upon whom Thou hast bestowed favors. Not (the path) of those upon whom Thy wrath is brought down, nor of those who go astray.
Two humans emotions - grace and anger - have been attributed to God in his own words. Now an ordinary bohra might be fooled by you in believing that the the quran is contradicting itself by first saying
"allahu ahad" - no human emotions - and then saying "sirat al ladhina anamta alayhim gairil magdhube alayhim waladuaaleen" - two human emotions -. But "allahu ahad" does not mean no human emotions, as explained above.
Those bohra scholars aren't too smart.
In other words, can he be concieved of being anything that is a human creation, physical or imaginary?
Not sure what you mean, but human emotions like grace or anger or any other human emotion for that matter, are not human creations. These are gifts from God.
Can he be experienced by humans?
According to you, what kind of experience would a human need to have to be able to say that he has experienced God?
Coming to the last ayah of ikhlas
112.004
YUSUFALI: And there is none like unto Him.
PICKTHAL: And there is none comparable unto Him.
SHAKIR: And none is like Him.
Hilali
"And there is none co-equal or comparable unto Him."
And then we have porus' translation
"There is nothing, no one like him "
I am not sure where it says that human like emotions cannot be ascribed to Allah. If there is such a translation please let me know.
If we find a human with 3 heads and 7 legs, then we won't have anything else like him either. Does it mean that it won't have the emotions that one headed humans have?
As I said before, those bohra scholars aren't too smart.