Thanks for the followup Matthew. I had a look at Wave Accounting, it looks interesting although I can see some negative reviews from some clients, I’ll investigate it my self once the business started.
As for revenue I still have no clear idea, which is why I’m being careful with expenses. As a first step I’ll keep my product with 370k downloads free, and just use it to drive traffic/awareness about my other products, some of which will be paid based on annual subscription, others will be free and will generate revenue from ads. I’ll also use my popular product to sell ads on the product itself, my users make a very specific type of audience so ads on it may well appeal to advertisers.
If none of the above works, I’ll have to do what I’m trying to avoid: turn my free “popular” product paid.