>Where do you get them from?

Search on www.yahoo.com and look for PIC & Basic and PIC & Forth.

>What is the best (easy-ish language, I/O, Basic Maths) interpreter to get,
>and where from? Cost?

What languages do you write?

>How is this accomplished in a processor such as the PIC16F84 which is only 8
>bit.... Looking at the spec sheet I see that it deals with 8 bits of data,
>and allows the remaining6 bits (of the 14 bit word) to be for the opcode.
>how do I accomplish my goal?

There is a "carry" bit which allows you to perform larger-than-8-bit maths
in several steps.

>Many thanks, And please be patient with my possibly "silly Questions", But I
>f I don't ask... I'll probably go mad trying to figure it out.

We were all newbies once.

Andy