Seventh of my system (5th of a riddle series)

Question

This is the fifth of the series,
are you becoming exhausted?
I'm the seventh of my system,
though not cold like that ice planet.

I can come with your order,
but you can order things without me.
I'm sometimes like a bounty,
which someone can put optionally.

If I'm looked at from above,
I'm read as an imagination.
I can be inscribed in some shapes
which can carry information.

Who am I?

Answer 1

Are you

The letter U?

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I'm the seventh of my system,
though not cold like that ice planet.

On a standard QWERTY keyboard, U is the 7th key on its row, starting from the Q in "QWERTY."

I can come with your order,
but you can order things without me.
I'm sometimes like a bounty,
which someone can put optionally.

When you order food, you can get flavour or flavor from your food. The letter U doesn't have to come, as it is "optional" in some words when it comes to European vs American spelling.

If I'm looked at from above,
I'm read as an imagination.

So I'm going to take this hint as meaning this: "looking in such a way from above that the subject is flipped vertically." And if we do that with "U", we get "∩", which most might call an arch. Hence, it being read as an "imagination", or how it literally looks as an image, rather than by its actual name (intersection symbol).

I can be inscribed in some shapes
which can carry information.

Obviously, the letter U can be inscribed on anything with writing. But if we take it further with Phylyp's observation about "shapes" possibly meaning street signs, we find that a common sign one might see on the road is one for a U-Turn.

Answer 2

I'd say you are:

The colour red

I'm the seventh of my system,
though not cold like that ice planet.

Red is the 7th colour in a rainbow (VIBGYOR)
Not cold = hot; red is often used to indicate heat

I can come with your order,
but you can order things without me.

Managers sometimes organize things with a RAG rating (red/amber/green)
However, that is not the only way of organizing things

I'm sometimes like a bounty,
which someone can put optionally.

Red can be used to highlight or otherwise bring attention to notices (e.g. a Red Notice used by Interpol)

If I'm looked at from above,
I'm read as an imagination.

Not sure of this, something to do with the letters r-e-d in the word dream?

I can be inscribed in some shapes
which can carry information.

Certain types of traffic signs/road signs are filled in with red (e.g. a no entry sign)