When we were at Zaal, the chef was quite adament the mixture should be 60/40 with the ginger being more. There are also plenty of threads / recipes on the site that suggest it should be the other way round. I think the mixture is 50 / 50 at jb's local TA. So really a matter of personal choice.
As for the tomato paste I normally use in the region of 2 to 3 tbs of the dilute with mine being diluted at a ratio of 2:1. Looking at many of the videos the chefs use just under a full chef's spoon of tomato paste / blended plumb tomatoes for most curries which suggests the quantities i'm using are somewhere in the right area. Unfortunately, not all recipes are specific enough about this.
Hope this helps