1) No. I mean there are some 3rd party open source projects that works with TL866 but last time I checked these were very limited in what it can do.
What people usually do is run the Windows software through Wine, seems to work well. There are some blogs and pages that describe what needs to be done in detail. For the price of T48 and what it can do, it's acceptable solution.
2) The software can do Chinese and English, with the latter perhaps a bit broken but usable. I haven's seen the T48 dedicated software but my own TL866 has some Chinese specific things even in English mode, like status bar shaded red for good and green for bad.
Note that due to cloning of the original TL866 by other Chinese manufacturers, the original was eventually somewhat secured and the software will detect cheaper clones. Either refuse to work with them, or even brick them. I assume the same for T48, if any clones exit. That's another reason for Windows-only closed software so be careful when buying. The current price is about 70USD from China on ebay and anything considerably cheaper is kinda suspect. Preferably pick a seller with good feedback on the very item you want to purchase.
One last warning, I belive some but not all of TL866 adapter sockets will work with T48. So if you need anything specific, also be careful when ordering. Make sure T48 is supported, as compared with older TL866 it's still a new product.