Hmm... if you do get promoted to MBBA you definitely need to increase your arena. On a minimum you need something like this to maximise your arena income:
Bleachers: 15000 (~$18)
Lower Tier: 2000 (~$65)
Courtside Seats: 400 (~$190)
Luxury Boxes: 25 (~$1200)
On ticket prices, this is not as straightforward. But the price in brackets are what most MBBA teams are charging for (And able to fill the seats). Roughly you will be able to get $500K of arena income.
But it is important to note that if you just promoted, you will definitely find it easy to get a fullhouse (For the first 4 weeks), so if you do get promoted, just charge maximum price or 95% of the maximum price if you want to be safe.
After the first 4 weeks, then you can start toning down the ticket prices to what was mentioned in the brackets. But this is always dependant on your team performance/fan survey. So you should compare with other similar MBBA teams to have a better feel.