I am reimbursed for part of the cost of part of the Medicare Part B premium on my Social Security payments. How do I report that?

If those are on your SSA-1099, they will automatically be placed in the correct places in TurboTax.

I have the same situation... SSA deducted $2,286.90 from my total SS payout for Medicare Part B Premiums. However, this amount was reimbursed by my pension plan. How do I account for that in TurboTax?

Do not enter the Medicare payments on the SSA-1099 in the TurboTax program since those payments were reimbursed.