Arabic

I've been trying to teach myself some rudimentary Arabic. I can identify and recognise Arabic numbers, which is a good start. So far my system is:

1 = like a one
2 = backward seven
3 = backward seven with a squiggly top line
4 = backward three squiggle
5 = tear drop (this would be by favorite shape of number)
6 = like a lazily drawn seven
7 = like a fancy V
8 = like an inverted fancy V
9 = just like an squiggly nine
0 = like a big full stop in the middle of the line

What seems odd to me, and nobody has yet been able to properly explain this, unlike Arabic text which is written from right to left, numbers when written in Arabic, are written from left to right. How did that happen?

The Greeks had a number system, but didn't understand the concept of 0. It was the Persians who gave the world 0. So how come their numeric system is opposite to the way of writing?

The Arabic character for 2 and the Arabic character for 3 seem very similar to me, so I'm going to be taking particular care when I check my finances.

As someone who has a bit of a lisp, I should get on fine here. There is apparently no true 'S' sound in Arabic.