The surviving spouse gets special treatment. She can avoid RMD's until after she is 70-1/2.
Non-spouse beneficiaries can roll the benefit, but only to an inherited IRA, so they get to keep taking RMD's.
These charts are helpful (to me, anyway): http://www.mhco.com/BreakingNews/ABene_Chart1_110813.html http://www.mhco.com/BreakingNews/ABene_Chart2_110813.html
I've heard different opinions on changing loans mid-year on SH Plans. It is not one of the limited items that has the IRS blessing as far as I know but since it generally doesn't have an impact on what is in the SH notice that some folks thing changing this is OK, and other think because it is not on the pre-set list changing it is not.
I think it has nothing to do with the type of contribution. The question is, is the plan self-directed or isn't it, and if so, then I think the answer as to "when" is "as soon as possible."
I would suspect that either payroll or the recordkeeper can't handle the catch-up properly. While the regs don't directly address Roth deferrals, I think that limitation violates the universal availability requirement. I also doubt that limitation is included in the plan document.