Well, it looks like you want to brew a lager so I would suggest the S-23 over the US-05. The US-05 is an ale strand. The S-23 is for lagers. I would pitch the whole packet also. Lagers generally need twice the yeast of an ale pitched because of the lower fermentation temperatures. I use two 11.5 gram sachets of S-23, rehydrated, when I brew 5 gallon batches.