Yeah your measuring it right, but you should also check out your shaft travel too. No point using the shocks if they don’t have enough for your bike.
Colour can be what ever you want but the correct colour is bronze or on some early Huskys they where black and ive seen some later early 80’s which were more of a red/moroon colour. Most people just go with the copper/bronze colour.
Springs were different colours. As OEM fitments they were often a colour that matched the bike eg Canams had orange but when you ordered after market springs they were different colours colour coded by a painted stripe to ID the rate.
Just depended on what bike and what rate springs. There was no set rule that said the short springs were one colour and the long ones another colour. pretty much pick the colours you want that suits your bike. A lot of people chose to now paint them black, yellow and blue.
New Ohlins springs are now Yellow & Black and the rates are printed on.
I have got stacks of photos but dont have time to post any. Just search on here or look through VMX mag to see what other guys ahave done or just do a Google 'image' search for Ohlins shocks or Ohlins remote reserervoirs or whatever and you will find some photos.
Yes that link looks about right, colour doesnt look quite right but it gives you an idea. There were different colour sticker designs too. Just get talking to Phillip at Husqvarna-parts.com and he will help you out