1) yes....3,99GB is Ok (4GB -2B)...limit data of FAT32 (FAT>>2GB -1B)
2) tiles of map.....your look with GmapTool in details . For ex, CN NT 3013.30 is 477 tiles (segment of map>>>>little maps)...but various value for map..also of very
3) supernumerary : 2025 tiles max?? Your 2 maps----> 2050 tiles

Bye,bye