Greetings and welcome.
To get rid of tracks you don't want I think you only have to right click on a blank part of the inspector part of the track and select DELETE from the drop down. I do this all the time to rid the project of unwanted tracks. Midi or audio, both work the same to delete.
MC5-LE is a stripped down version of MC5. However, I would think it would still recognize the USB inputs.
I'm going to make this next statement based on your comment that .... "If possible I'd like to get this to work as is, if not, I'll do whatever I have to, new laptop, with Win 7 or 8, external soundcard/interface, whatever, I like the keyboard so I won't change that."
So..... Get the full version on MC6 (touch is most recent) and purchase a nice USB audio/midi musical interface .... M-Audio, Presonus, Focusrite.... , and be sure it can run ASIO drivers right out of the box. Get an interface, not a gimmick box that includes a mixer or a guitar POD integrated with the interface..... straight up solid interface is what you want. So...for about $300 you get MC6 and a new interface and that should resolve the problems. Plug the keyboard into the interface (5 pin did midi connection) and you are ready to rock.
Using a full version of MC and a solid interface will let you do what you want with ease, and the DAW gear becomes transparent in the recording process..... you can concentrate on the music, not working the gear.
While Cakewalk does have certain minimum computer specs, you should be OK with any modern computer as the basis for your studio. I have an old Dell lappy with a duo core, running Vista, and my main desktop DAW is an i3 quad core running XP/32. The minimum specs are guidelines so that the DAW runs smoothly and efficiently. I have run some Cake products (many years ago) on a sub-spec machine. It took a little longer to "think" before it did something but the playback and recording was generally smooth as you would want.
Hope this helps