You have a new model. I have never heard of a MODEL10 before. As such, it will be difficult to advise you on your problems, except to say that a 5 volt charger wont charge a '9 volt' (actually the battery will be 7.2 volts) battery.
The x200 and x210 processor do not support GPS, the x220 however, does support GPS, so if the GPS works it probably is a x220, unless the pcb is substantially different from its predecessors and it has a seperate GPS receiver built on the pcb.
The internal memory is interesting, it may be that the tf card in the internal slot is indeed mis-reporting itself.. the best way to check it is to remove it, plug it into a PC and run h2testw.exe on it. (google for it)( you will have to re-flash the tablet afterwards so if you want to go down this route make sure you have the files and the procedure to get a working system back). If it passes that then maybe there is some soldered in memory as well as the card. It is normal to partition larger than 4GB cards into two or more partitions as the Android system cannot live on a large partition.
Different models of FT3 have different methods of commencing a flash, trying the wrong method wont brick the tablet... it just wont flash, however, if you use the right method of flashing but use a corrupt or incorrect file then it may brick it. I suggest you contact the seller and ask them for both the procedure and a link to the files.
The battery is what it is....if there are no markings (and even if there are they may be wrong!) then the only way of finding out what capacity is is by charging it fully and monitoring the discharge rate and the duration, try battery monitor widget pro.apk Multiupload.com - upload your files to multiple file hosting sites!
you will have to fully charge the battery and then discharge it until it switches itself off, maybe more than once to get a reasonably reliable figure.
oh...and dont try and fit the gps antenna inside... it wont fit and even if it did.. it wouldn't work in there....