Mike I have never used a 488 but it should be like all the rest of the tascam cassette units. As for your faders are you turning up the trim controls at the top of the channel strip?
If you missed that set your fader to the 7 to 8 level, their should be a kinda area marked on the fader section for that, Kind of a grey area. This is the best spot to set your fader on recording, Then turn the trim level up or down to set the levels on your meters. Unless you get to much signal then you will need to turn the trim control all the way down(to the left) and lower you fader so the meters are reading a good signal that your machine and tape can handle.
As for the shure 55s no its not the best mic in the world for recording but play with it and try some differant things with it you never know what you might come up with and it just may sound good on some things.
I hope this makes sense and helps.Let us know how it goes. Happy Recording