Also don't worry about the file size, you can guess it from the size of the extracted files and the program will tell you when it's too big.
Also the program will take all the information about the file, including the loop data, from the first file, which means that ,even if you have different loops for both the files you want to insert, it will take the loop from there, I just advise you to loop both to be sure.
Also about the exporting as .wav, you should export as 16 bit and if the track you want to import is stereo you first have to make it into 2 mono channel files by clicking on the name of the track here Link and then going to split stereo to mono and then closing one of the tracks and then exporting it again or directly starting with setting the loop.
Repeat this and close the other track this time to make the other mono channel.