F you received a lump sum pension that you rollover into an IRA, and then begin withdrawing from it, is that still pension money when computing income taxes?

The tax treatment of pensions and IRA is the same for federal tax purposes.  For state taxes, it depends on the state.  There are states that do not tax pension income, but do tax IRS withdrawal.  If you rolled over a lump sum payment from a pension to an IRA, it is no longer a qualified retirement plan, it is an IRA and will be taxed accordingly.