1) I understand that you get commission for financial services that you offer.
2) If so, you are treated as a commission agent and you need to obtain registration under GST irrespective of threshold limit for turnover (i.e. ₹20 lacs threshold limit is not applicable for commission business).
3) It is not compulsory for you to have current account at the moment, even savings account can be used for your initial business purpose because initially the frequency of transactions will be less. You may subsequently open current account for ease of doing business.
4) Regarding taxes, I had already informed you that income tax rates as per slabs in case of individuals will be applicable in this case (this is applicable even for proprietorship concerns). You need to charge GST @ 18% on the commission that you earn.