By taking the PFMV on 12/31 of previous year for all IRA accounts (Roth doesn't have RMD) and divide your age factor. i.e PFMV = $100,000 and age factor is 22.7 then the RMD would be $4405.29 RMD...
No, you are not required to contribute in one lump-sum. You can pay into your IRA over a 15 month period whenever you like as long as it is paid according to your agreement before tax day on April...