I am looking for some guidance and good reference material to teach me how to calculate a bottom's up and "straight" QNEC. Any suggestions?

lets say my ADP for the HCEs is 5% and the ADP for the 15 NHCEs is 2.5%.
I failed my test by 0.5%
In other words I need to raise the NHCEs by 15 * 0.5% or total of 7.5%
If plan document allowed for it, I could give a 7.5% bottom up QNEC to the lowest paid ee (providing he/she doesn't go over the 415 limit) If that ee was at 20% already, then I could only give him/her 5% and I qould have to give the next NHCE a 2.5% QNEC.
or if plan does not allow for bottom up QNEC I still need to allocate a total of 7.5%. if only 10 of the 15 NHCEs are eligible for a QNEC, then each of those 10 NHCEs would receive .75% QNEC.

Why would there be some employees on the ADP test as eligible employees but not eligible for the QNEC? It appears that it is quite simple--- what am I missing?

You may place restrictions on the QNEC; such as 1000 hour or last day. Therefore a person may be eligible to defer, but not be eligible for the QNEC.

Does the same apply for the QMAC, as far as calculating? I am aware that the QNEC is coded as ee contributions and the QMAC is coded as er contributions --- correct?