(1) 1Mb is 1M bits per second, 1 byte is 8 bits and it will take 10bits to transfer due to overhead (for error correction etc).
so your up limit is about 100 kb/sec, average 50-85 is normal
(2) you have "fast" connection, but another end may have small connection, also many users may try to download from the same server you are downloading, i.e. the download speed is also limited by whoever provide you file for download
(3) Maybe you should consider to change ISP because a lot os users(including myself) never have any session dropping problem even with home service. I assume that the business service should be more reliable.