Here are answers for your questions :-
1. Does the monthly cost of the reseller accounts include unlimited MSSQL servers or is this extra?
Ans :- Yes. You can setup unlimited MSSQL Server databases under all your client accounts.
2. If you reach the bandwidth quota of one reseller option can you upgrade to the higher bandwidth option?
As :- Yes. You can upgrade to next higher plan as and when needed. You will need to pay for the difference only if you choose yearly payment option. In case of monthly payment option the difference would be nominal depending on the day of month you decide to upgrade.
3. Is is possible to do automated customer signup, so they sign themselves up through my
website hosting? What payment gateways do you recommend?
Ans :- We provide you with many payment gateways and automated signup system. You can choose any payment gateway like authorize.net, worldpay, paypal, 2checkout depending on which merchant gateway is more feasible for your business. We would recommend to get started with paypal and 2checkout as both this payment gateways have good security features and its much easier to filter fraud signups with this gateways. Major problem with authnet and worldpay is fraud signups and you will personally need to go through all signups for verification in case of authnet and worldpay.