Improvisation

Morning Paul. Answers below...

"Reference chorus 2 on Temperature, as an example, how would I turn the first four bars into A A1 A2."
You would play the first four bars (A) as written. When repeating it (bars 5-8) for A1 you would commonly change the presentation of the same notes with possibly some simple changes to rhythm/texture. A simple way to do it would be to move it all up one octave (starting on 4 draw). The last A (A2) you could play it in octaves (1/4 etc.)

"If I were to Use the first two bars then went up an octave for bars 3 and 4 would this be an A or A with fills"
That's just A. If you were to repeat your first two bars for bars 5 and 6 (acting as your A) and then change your lick for bars 7 and 8, then that context turns bars 3 and 4 and 7 and 8 into fills. So, it's what you do in bars 7 and 8 that make bars 3 and 4 a fill or not. All material in bars 1-4 can just be A, it depends on what you do in the next four bars (if you were to just repeat all of what you played in bars 1-4 for bars 5-8, then it's just an A).

"If I were to use bars one and three then placed different notes in bars 2 and 4 would this still be an A"
Yes

"and would this apply to bars 5 to 8"
If you change in bars 6 and 8 then bars 2 and 4 are now fills.

"whats the difference between a fill and a variation"
A fill is filling space... commonly bars 3-4 and 7-8, and 11-12 turnaround area can be thought of that as well. A variation is based on a previously-presented idea and must not be changed so much that the relation is not apparent.

Glad I could be of help. You have a good day as well.