I don't know if there is such an animal, but I would like a utility that shows all the commands (organized sorted or by function group) and when you choose the command to allow you to give you a form to fill in any options. Then click execute and pop you over to a terminal.

I guess that would be the basic use of it. Of course it should be extensible (ie allow you to download a new database of the latest commands).

Is there such a thing? I tried searching but could not find anything.

Some comments-

The only like that I've seen are some pieces of code that sit on top of the shell and provide a VAX/VMS-like comand line interface.
It expects that you know VMS DCL already. Windows PC's have the reverse available- a unix interface - cygwin.

Depending on the shell you use, those commands may be different like: export vs setenv for example.

Just because I haven't seen it doesn't mean there isn't one.

Your best option is to get a copy 'unix in a nutshell' - the Oreilly book. Keep it at your terminal - it has cross referencing like

Delete - see rm

And it groups related commands.

Plus, a lot of stuff you do involves piping to multiple commands
like:
> ll | grep "Oct" | grep -v "2002"

to find files dated October this year but not last year "2002"
So you just have to learn on your own or sit by an experienced user for a while.